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Vol.  6,  No.  15,  pp.  353-468,  plates  33-48 


June  17,  1911 


THE    GENUS    GYROCOTYLE,  AND    ITS 

SIGNIFICANCE    FOR   PROBLEMS 

OF  CESTODE   STRUCTURE 

AND    PHYLOGENY 


BY 


EDNA  EARL  WATSON 


BERKELEY 

THE   UNIVERSITY  PRESS 


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of  San  Diego.) 

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Pp.  45-51,  plate  1.    December,  1904. 

Nos.  1  and  2  in  one  cover 60 

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by  William  E,  Bitter.    Pp.  51-112,  plates  2-3.    31  text-figures.  Jan- 
uary,   1905    .65 

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1905    '..- 1.00 

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7.  The  Behavior  of  Corymorpha,  by  Harry  Beal  Torrey.    Pp.  333-340, 

5  text-figures. 

Nos.  6  and  7  in  one  cover - 25 

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Genus  of  the  Peridinidae,  by  Charles  Atwood  Kofoid.    Pp.  341-368, 

plates  17-19.    January,  1906  _ 26 

Index,  pp.  369-382. 

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UNIVERSITY    OF    CALIFORNIA    PUBLICATIONS 

IN 

ZOOLOGY 

Vol.  6,  No.  15,  pp.  353-468,  plates  33-48  June  17,  1911 


/"    'Of    THE  A 

I   UNIVERSITY    ) 

v        or      y 

X^UFORJj^ 

^^^SBHESOMBB^^^^ 


THE    GENUS    GYROCOTYLE,    AND    ITS 

SIGNIFICANCE    FOR   PROBLEMS 

OF   CESTODE    STRUCTURE 

AND  PHYLOGENY* 

BY 

EDNA    EARL    WATSON 


CONTENTS. 

PAGE 

A.  Introduction   354 

B.  History  of  the  Genus  356 

C.  Gyrocotyle  of  the  Coast  of  California  363 

I.     Occurrence  and  Host  363 

II.     Gross  Anatomy  366 

III.  Behavior  of  Living  Animal  371 

IV.  Characteristics  for  Separation  of  Species  376 

V.     Key  to  Species  of  Gyrocotyle  382 

D.  Morphology  and  Histology  of  Gyrocotyle  383 

I.  Material  and  Methods  383 

II.  Body-covering  and  Spines  384 

III.  Musculature  389 

IV.  Reproductive  Organs  395 

V.  Formation  of  Compound  Egg  and  Cleavage  ,  406 

VI.     Excretory  System  407 

VII.     Nervous  system  409 

VIII.     Sense  Organs  417 

E.  General  Discussion 418 

I.     Cuticula  419 

II.     Orientation  421 

F.  Summary   431 


*  A  dissertation  presented  to  the  Faculty  of  the  College  of  Natural 
Sciences,  in  the  University  of  California,  in  partial  satisfaction  of  the 
requirements  for  the  degree  of  Doctor  of  Philosophy.  April,  1910. 


218265 


354          University  of  California  Publications  in  Zoology.     CV°L-  6 

A.  INTRODUCTION. 

The  Cestodaria  (Monticelli,  1892)  or  monozoic  cestodes 
(Lang,  1891),  including  Amphilina,  (Rud.),  Archigetes  (Ratz) 
Caryophyllaeus,  (Rud.)  Gyrocotyle,  (Diesing)  and  Wageneria 
(Wag.)  are  of  peculiar  interest  to  students  of  the  platyhelminths. 
They  occupy  a  position  intermediate  between  the  merozoic  ces- 
todes and  the  trematodes,  being  allied  to  the  latter  by  the  general 
arrangement  of  the  reproductive  organs  and  by  their  funda- 
mentally unitary  character,  and  distinguished  from  them  by  the 
absence  of  a  digestive  tract.  This  last  characteristic  allies  them 
with  the  merozoic  cestodes,  from  which  they  are  distinguished 
on  the  other  hand  by  their  unsegmented  condition  and  by  the 
accompanying  absence  of  segmental  repetition  of  the  genital 
organs,  as  stated  by  Monticelli  (1892).  The  group  is  difficult 
to  consider  as  a  whole  because  of  the  remarkable  diversity  shown 
in  its  four  well-established  genera,  both  as  to  structure,  life-his- 
tory and  host.  The  characters  mentioned  above  practically 
exhaust  those  common  to  the  group,  and  each  genus  possesses 
characters  of  such  rank  as  fittingly  to  receive  ordinal  distinction 
in  classification.  Two  of  the  genera,  Archigetes  and  Wageneria, 
have  but  one  species  each.  Two  each  have  been  assigned  to 
Caryophyllaeus  and  Amphilina,  and  at  least  four  are  now  recog- 
nized in  the  genus  Gyrocotyle.  The  grounds  on  which  specific 
distinctions  have  been  made  are  far  from  satisfactory.  These 
considerations  indicate  that  the  group  is  not  only  phylogenetic- 
ally  intermediate  but  composed  of  very  old,  long-established 
forms,  on  which  the  forces  that  make  for  speciation  have  long 
since  ceased  to  act.  The  Cestodaria  are  either  remnants  of  a 
once  large  and  differentiated  group,  or  they  are  members  of  a 
class  never  differentiated  to  any  considerable  extent.  They  are 
presumably  of  greater  age  than  the  cestodes,  their  hosts  being 
invertebrates  or  primitive  vertebrates.  Cestodes  are  phylogen- 
etically  the  youngest  of  the  platyhelminths,  since  the  host  in 
the  sexual  period  is  always  a  vertebrate.  They  have  been  greatly 
and  variously  modified  by  their  parasitic  habit,  and  they  present 
problems  of  structure  and  development  of  extreme  difficulty.  It 
seems  probable  that  much  help  towards  the  solution  of  these  can 


1911]  Watson:  The  Genus  Gyrocotyle.  355 

be  obtained  through  an  exhaustive  study  of  the  Cestodaria,  the 
nearest  surviving  relatives  of  the  merozoic  cestodes;  and  in  this 
possibility  lies  the  chief  interest  pertaining  to  the  former  group 
and  to  this  investigation. 

Lonnberg  (1897),  in  a  study  of  the  phylogeny  of  parasitic 
platyhelminths,  discusses  the  possible  phylogenetic  significance 
of  the  Cestodaria  and  comes  to  the  conclusion  that  they  cannot 
be  regarded  as  ancestral  forms  of  the  merozoic  cestodes : 

"Die  jetzigen  polyzoischen  Bandwurmstrobilen  sind  natiirlich  aus 
monozoischen  Formen  hervorgegangen.  Die  noch  jetzt  existierenden 
monozoischen  Cestoden  konnen  aber  kaum  als  Stammformen  der  poly- 
zoischen angesehen  werden.  .  .  .  Diese  [Gyrocotyle  and  Amphilina] 
sind  wahrscheinlieh  beide  urspriinglieh,  weichen  aber  in  mehreren  Hin- 
sichten  von  den  echten  Cestoden  recht  sehr  ab.  Gyrocotyle  ist  durch  das 
Erweben  von  Haftorganen  an  beiden  Korperenden,  das  Trichterorgan 
am  Vorderende  und  das  Acetabulum  am  Hinterende,  unfahig  geworden, 
sich  weiter  zu  entwickeln. ' ' 

While  the  writer  is  convinced  of  the  essential  correctness  of 
Lonnberg  ?s  general  contention,  that  the  ancestors  of  cestodes 
must  be  sought,  not  among  Cestodaria  or  trematodes,  but  among 
Turbellaria,  it  is  felt  that  he  undervalues  the  evolutionary  sig- 
nificance of  the  Cestodaria.  The  merozoic  cestode  is  probably 
not  the  descendant  of  any  monozoic  cestode  now  in  existence ; 
but  because  of  the  fundamental  similarity  between  the  two 
groups  we  may  ^.ope  to  find,  in  the  simpler  forms  meeting  the 
same  problems  in  essentially  the  same  way,  some  clue  to  the 
manner  in  which  occurred  the  complicated  processes  by  which 
the  hypothetical  turbellarian-like  ancestor  was  transformed  into 
the  merozoic  cestode.  Naturally,  those  cestodes  which  are  second- 
arily monozoic,  Arckigetes  and  Caryophyllaeus  (Lonnberg,  1897) 
are  of  little  value  in  this  sense.  Amphilina  (Acipenser)  and 
Gyrocotyle  (Chimaera)  are  primarily  monozoic,  inhabit  hosts 
of  great  phylogenetic  age,  and  show  fundamental  correspondence 
to  the  typical  cestode  structure  in  all  important  respects.  Gyro- 
cotyle, the  genus  with  which  this  paper  is  concerned,  Lonnberg 
regarded  as  off  the  line  of  cestode  evolution,  side-tracked  by  the 
development  of  organs  of  attachment  at  both  ends.  The  writer 
hopes  to  show  that  only  one  functional  organ  of  attachment  is 
present,  that  this  is  homologous  to  the  cestode  scolex,  although 


356          University  of  Calif  or  n  ia  Publications  in  Zoology.     tv°L-  6 

much  simpler,  and  that  its  structure  and  position  afford  very 
significant  indications  of  the  origin  and  primitive  location  of  the 
cestode  scolex.  The  evidence  of  this  homology  and  its  theoretical 
significance  will  be  discussed  later;  the  point  of  chief  interest 
now  is  that  the  very  structural  peculiarity  which  Lonnberg 
regarded  as  removing  Gyrocotyle  from  any  great  phylogenetic 
interest  is  the  source  of  its  most  significant  and  interesting 
contribution  to  the  solution  of  the  problem  of  cestode  origins. 

This  investigation  has  been  carried  on  in  the  Zoological  Labo- 
ratory of  the  University  of  California  and  at  the  Station  of  the 
Marine  Biological  Association  at  La  Jolla.  For  material  I  am 
indebted  to  Professor  C.  A.  Kofoid,  and  through  him  to  the 
United  States  Bureau  of  Fisheries  and  the  Marine  Biological 
Association  at  La  Jolla;  also  to  Professor  Jacques  Loeb,  for 
privileges  at  the  Herzstein  Research  Laboratory  at  Monterey. 
For  substantial  assistance  in  the  preparation  of  drawings  for 
publication  I  am  indebted  to  Miss  E.  J.  Eigden.  For  the  point- 
ing out  of  this  line  of  investigation,  for  help  in  obtaining  the 
obscure  and  not  easily  accessible  literature  of  the  subject,  and 
for  counsel  and  encouragement,  I  wish  to  express  my  debt  to 
Professor  Kofoid,  under  whose  direction  this  work  has  been 
brought  to  its  present  state  of  completion. 

B.  HISTORY  OF  THE  GENUS. 

The  history  of  the  genus  Gyrocotyle  is  complicated  by  con- 
flicting reports  as  to  its  systematic  position,  its  habitat,  its  orien- 
tation and  its  morphology.  The  genus  was  established  by 
Diesing  (1850),  for  a  parasite  obtained  by  Gueinzius  in  1842 
from  Antilope  pygarga,  a  South  African  ungulate.  This  report 
was  an  error  (Diesing,  1858,  p.  492),  but  was  accepted  as  correct 
for  several  years,  contributing  in  no  small  degree  to  the  confusion 
concerning  the  habitat  and  systematic  position  of  the  genus.  In 
1844  Krb'yer  showed  Diesing  a  parasite  similar  to  that  collected 
by  Gueinzius,  taken  from  inside  the  shell  of  an  edible  mollusk 
(Diesing,  1855).  These  two  specimens  were  grouped  in  one 
species  by  Diesing  (1850)  under  the  new  genus  Gyrocotyle,  and 
described  in  the  following  terms: 


1911]  Watson:   The  Genus  Gyrocotyle.  357 

"Corpus  sub-ellipticum  depressum;  os  subterminale  corpore  con- 
tinuum; os  subterminale  anticum  exiguum;  acetabulum  unum  in  extremi- 
tate  caudali  terminale,  sessile,  orbiculare,  disce  in  gyros  plicata;  penis 
ventralis  superus  lateralis;  apertura  feminea  infra  penem  centralis; 
porus  excretorius  dorsalis  supra  acetabulum."  [Quoted  from  Braun 
(1889)]. 

The  genus  as  thus  denned  contained  only  a  single  species, 
Gyrocotyle  rugosa.  Diesing  referred  the  genus  to  the  trematodes, 
placing  it  near  the  genus  Amphistomum  because  of  the  posterior 
position  of  its  acetabulum.  In  1855,  in  his  description  of  the 
collection  of  endoparasitic  worms  made  by  Natterer  in  Brazil, 
Diesing  published  a  second  description  of  the  genus  identical 
with  the  first,  with  five  figures  and  a  discussion  of  the  habitat 
and  systematic  affinities  of  the  genus.  He  regards  it  as  improb- 
able that  both  Mactra  edulis  and  Antilope  pygarga  are  true  hosts 
of  Gyrocotyle,  and  believes  that  the  report  of  its  occurrence  in 
Mactra  is  an  error.  In  case  Mactra  should  prove  to  be  the  true 
host,  he  concludes  that  Gyrocotyle  as  an  ectoparasite  would  have 
to  be  referred  to  the  Bdellidea.  As  an  endoparasite  of  Antilope, 
he  places  it  under  the  trematodes.  Diesing  made  no  attempt  at 
a  study  of  the  internal  structure  of  the  parasite  and  apparently 
only  a  cursory  examination  of  its  external  appearance.  From 
his  figures  it  seems  probable  that  his  specimens  were  in  a  state 
of  decomposition  when  preserved. 

In  1852  Wagener  described  and  figured  a  parasite  found  by 
himself  and  Grube  in  the  spiral  valve  of  Chimaera  monstrosa, 
at  Nice.  For  this  he  established  the  genus  Amphiptyches,  con- 
taining a  single  species,  urna,  and  referred  this  genus  to  the 
cestodes  because  of  its  morphological  resemblance  to  that  group. 
Wagener  made  a  careful  study  of  the  internal  structure  of  the 
worm,  both  in  the  living  animal  and  preserved  specimens  made 
partially  transparent  by  clearing.  Except  for  confusion,  as  to 
the  ducts  of  the  genital  organs  and  in  a  few  minor  details,  his 
figures  are  correct.  Diesing 's  (1855)  description  and  figures 
convinced  Wagener  that  Amphiptyches  was  identical  with  Gyro- 
cotyle. In  a  letter  to  Diesing  (1857)  he  calls  the  latter 's  atten- 
tion to  Amphiptyches  urna,  and  in  his  ' '  Enthelminthica  No.  V. ' ' 
(Wagener,  1858),  he  discards  Amphiptyches  as  a  generic  name 
and  retains  it  as  a  specific  name  for  the  form  discovered  by  him : 


358          University  of  California  Publications  in  Zoology.     ITOL- 


Gyrocotyle  amphiptyches.  Diesing  ("Revision  der  Myzhelmin- 
then,"  1858)  recognizes  Amphiptyches  as  a  distinct  genus,  plac- 
ing it  near  Amphistomum  under  trematodes,  in  the  place  occupied 
in  his  earlier  paper  (1855)  by  Gyrocotyle,  then  considered  an 
ectoparasite  of  Antilope  pygarga.  He  supposes  Amphiptyches 
to  have  a  mouth,  digestive  tract  and  anus,  in  the  face  of  Wag- 
ener's  (1852,  p.  547)  explicit  statement  to  the  contrary.  He 
gives  as  its  habitat  the  gills  and  intestinal  tract  of  Chimaera 
monstrosa.  His  own  genus,  Gyrocotyle,  he  puts  under  the 
Bdellidea  near  Malacobdella  (Diesing,  1858,  p.  492).  He  makes 
certain  changes  in  the  generic  description,  the  most  important  of 
these  being  in  the  interpretation  of  the  ventral  canal  opening 
(proboscis  of  Spencer)  ;  in  his  description  of  1850  he  regards 
it  as  an  excretory  pore,  in  1858  as  the  anus.  The  change  was 
made  in  order  to  place  the  genus  under  the  Bdellidea,  where 
Diesing  was  convinced  it  belonged  if  Mactra  was  its  true  host. 
That  the  report  of  its  occurrence  in  Antilope  was  an  error 
Diesing  had  discovered  in  the  interval  between  1855  and  1858r 
and  it  was  probably  due  to  this  discovery  that  the  change  in  the 
position  of  the  genus  was  made  (Diesing,  1858,  p.  492). 

Diesing 's  disposition  of  Amphiptyches  was  apparently  not 
satisfactory  to  Wagener,  for  in  his  paper  "Ueber  Amphilina 
foliacea,  Gyrocotyle  Diesing  und  Amphiptyches  (Grube  and 
Wagener)"  (1858),  Wagener  definitely  withdraws  Amphip- 
tyches, recognizing  his  form  to  be  a  species  of  Diesing 's  older 
genus.  In  Diesing 's  '  *  Nachtrage  und  Verbesserungen  zur  Revision 
der  Myzhelminthen  "  (1859),  he  agrees  with  Wagener  in  placing 
the  two  species  under  one  genus,  which  he  refers  to  the  "Bdel- 
lidea monocotylea. " 

The  two  species  are  distinguished  one  from  the  other  only 
by  the  absence  of  spines  and  lateral  frills  and  the  smaller  size 
of  the  "tail  rosette"  in  Gyrocotyle  rugosa. 

Diesing  (1859,  p.  448)  regards  the  genus  as  typically  ecto- 
parasitic  on  marine  mollusks,  assuming  that  the  species  of  Grube 
and  Wagener  has  its  normal  habitat,  not  in  Chimaera  monstrosa, 
but  rather  on  some  of  those  mollusks  whose  fragments  occur  in 
the  intestine  of  the  fish.  "Da  Gyrocotyle  rugosa  aus  einem 


1911]  Watson:  The  Genus  Gyrocotyle.  359 

Mollusken,  namlich  der  Mactra  edulis  stammt,  so  1st  es  sehr  wahr- 
scheinlich,  dass  auch  die  von  Grube  und  Wagener  beschriebene 
Art  ihren  eigentlichen  Wohnort  nicht  in  der  Chimaera  mon- 
strosa,  sondern  vielmehr  in  einer  jener  Mollusken,  deren  Frag- 
mente  sich  im  Darme  des  Fisches  verfanden,  habe." 

Van  Beneden  and  Hesse  (1864),  maintain  the  two  genera  and 
refer  both  to  the  Hirudinea  as  the  "  Malacobdellaria  dioici." 
These  authors  agreed  with  Diesing  in  regarding  a  mollusk  as  the 
true  host  of  Amphiptyches,  stating  explicitly  that  it  is  not  to  be 
considered  a  parasite  of  Chimaera,  but  as  having  been  taken  in 
by  chance  with  the  mollusk  on  which  the  fish  feeds.  Later  Van 
Beneden  (1869)  withdrew  from  this  position  and  classed  Amphi- 
ptyches as  a  true  parasite  of  Chimaera. 

No  further  work  was  done  on  either  of  these  forms  until 
Monticelli's  "Saggio  di  una  morfologia  dei  trematodi"  (1888)  in 
which  he  excludes  Gyrocotyle  and  Amphiptyches  from  the 
trematodes,  referring  Gyrocotyle  to  the  bdellodes,  near  Malacob- 
della,  following  Hesse  and  Van  Beneden.  He  affiliates  Amphi- 
ptyches with  the  cestodes,  suggesting  that  Amphilina  and  Amphi- 
ptyches are  closely  related  forms,  the  latter  being  the  simpler  of 
the  two,  and  together  should  be  regarded  as  forms  transitional 
between  trematodes  and  cestodes.  Shortly  after  this  Monticelli 
(1889b)  compared  the  specimens  of  Gyrocotyle  and  Amphi- 
ptyches available  in  the  museums  of  Leipzig,  Berlin  and  Vienna. 
As  a  result  of  the  comparison  he  says : 

' '  Io  ho  potuto  stabilire  con  certezza  la  loro  posizione  sistematica 

desumendola  dai  loro  caratteri  anatomic!  ed  embryologici.  Dalle  mie 
recerche  sono  perVenuto  alle  seguenti  conclusion!: 

"1.  Che  1'  Amphiptyches  ed  il  Gyrococtyle  devono  considerarsi,  come  gia 
pensavano  il  Wagener  ed  il  Diesing,  due  specie  distinte  del  gen.  Gyro- 
cotyle. Le  due  specie  si  chiameranno:  G.  rugosa  Diesing  e  G.  urna  Grube 
e  Wagener. 

"2.  Che  il  gen.  Gyrocotyle  deve  allogarsi  fra  i  Cestodi  e  riguardarsi 
affine  all '  Amphilina. ' ' 

He  goes  on  to  say  that  the  first  conclusion  rests  on  remarkable 
uniformity  of  structure;  the  sole  external  difference  being  the 
lack  or  slight  development  of  the  lateral  folds  in  Gyrocotyle. 
The  second  conclusion  rests  on  the  mode  of  development  and 
internal  structure  of  both  species.  The  similarity  of  cestodarian 


360          University  of  California  Publications  in  Zoology.     [VoL-  6 

organization  to  that  of  the  cestodes  is  then  pointed  out  in  the 
musculature,  the  lack  of  a  digestive  tract,  the  arrangement  of 
the  excretory  system,  the  general  form  of  the  nervous  system, 
the  arrangement  of  the  genital  organs,  and  the  presence  of  a 
six-hooked  embryo,  in  Gyrocotyle  rugosa. 

In  the  same  year  (1889c),  in  examining  the  Entozoa  of  the 
British  Museum,  Monticelli  found  an  undoubted  example  of 
G.  rugosa,  taken  from  Callorhynchus  antarcticus  at  Dunedin,  New 
Zealand.  As  he  points  out  (1890),  G.  rugosa  had  up  to  this  time 
been  reported  only  from  Mactra  edulis,  G.  urna  only  from 
Chimaera  monstrosa.  He  summarizes  his  conclusion  as  follows : 

"1.  Che  il  genere  Gyrocotyle  e  parassita  proprio  della  famiglia  delle 
Chimaeridae. 

"2.  Che  i  due  generi  finora  conosciuti  della  famiglia  (Chimaera  e 
Callorhynchus)  albergano  ciascuno  una  specie  del  genere  Gyrocotyle. 

"3.  Che  il  genere  Gyrocotyle  perviene  nelle  Chimaeridae  per  mezzo 
di  molluschi  bivalvi. " 

Monticelli  discusses  the  question  whether  Mactra  edulis  is  to 
be  regarded  as  the  true  intermediate  host  of  G.  rugosa,  and  con- 
cludes that,  since  the  example  found  in  the  mollusk  contained 
hooked  embryos,  a  third  host  must  be  found  to  convey  G.  rugosa 
to  Mactra.  He  suggests  that  possibly  some  of  the  mollusks  on 
which  Chimaera  monstrosa  feeds  (probably  some  member  of  the 
Cyprinidae),  may  be  the  intermediate  hosts  of  G.  urna. 

This  work  of  Monti  celli's  definitely  settles  the  question  as  to 
the  generic  identity  of  Gyrocotyle  and  Amphiptyches,  and  estab- 
lishes two  species  of  the  genus  Gyrocotyle,  separated  by  three 
distinct  characters.  Further,  it  indicates  that  G.  rugosa  is  a  true 
parasite  of  Callorhynchus,  though  this  point  could  hardly  be 
considered  as  established  by  a  single  occurrence  of  the  parasite 
in  the  fish. 

Further  evidence  on  this  question  was  supplied  by  Spencer's 
(1889)  report  on  the  morphology  of  three  specimens  of  Gyro- 
cotyle found  by  him  in  the  mouth  of  a  specimen  of  Callorhyn- 
chus antarcticus.  These  Spencer  referred  to  Wagener's  Amphi- 
ptyches urna,  but  from  the  form  of  the  lateral  frills  and  the 
presence  of  hooked  embryos,  it  seems  quite  clear  that  his  species 
was  not  G.  urna,  but  G.  rugosa.  (See  my  pi.  38,  fig.  36).  This 


1911]  Watson:  The  Genus  Gyrocotyle.  361 

view  is  substantiated  by  Monticelli's  identification  of  a  specimen 
from  C.  antarcticus  as  G.  rugosa,  Diesing 's  original  species, 
though  the  size,  number  and  character  of  the  frills  of  the 
terminal  rosette  as  figured  by  Spencer  do  not  agree  with  Diesing  's 
original  figure  of  those  structures. 

Braun  (1889)  published  a  careful  review  of  the  literature 
of  the  genus  up  to  and  including  Monticelli's  (1890)  paper  on 
the  finding  of  Gyrocotyle  rugosa  in  Callorhynchus  antarcticus, 
but  not  including  Spencer's  paper.  He  reduces  Amphiptyches 
to  a  synonym  of  Gyrocotyle. 

Lonnberg  (1890a)  mentions  the  finding  of  Gyrocotyle  in 
July  and  August,  near  Bergen.  He  later  (1890b)  published  a 
short  paper,  "Ueber  Amphiptyches  Wag.  oder  Gyrocotyle  urna 
(Grube  et  Wagener)  Diesing."  In  a  subsequent  paper  (1891) 
he  includes  a  detailed  study  of  Amphiptyches  urna,  covering  the 
questions  of  synonymy,  systematic  position,  occurrence,  habitat, 
behavior,  orientation,  and  morphology,  concluding  with  a  com- 
parison of  Amphiptyches  with  the  other  genera  of  the  Cesto- 
daria.  Lonnberg  agrees  with  Wagener  in  regarding  Gyrocotyle 
as  a  true  cestode ;  he  considers  it  the  most  primitive  of  the  mono- 
zoic  cestodes  and  the  most  closely  related  to  the  trematodes.  He 
does  not  accept  the  combination  of  Gyrocotyle  and  Amphi- 
ptyches in  one  genus,  and  regards  the  form  investigated  by  him, 
from  Chimaera  monstrosa,  as  Amphiptyches  urna.  Aside  from 
his  careful  study  of  this  species,  which  will  be  referred  to  later, 
Lonnberg 's  most  important  contribution  to  the  knowledge  of 
the  genus  was  his  description  of  the  animal  in  the  living  condi- 
tion and  the  various  forms  assumed  by  it.  Its  behavior  and 
appearance  he  describes  as  being  in  the  majority  of  cases  similar 
to  that  described  by  Wagener,  namely,  pointed  at  one  end,  with 
marginal  frills  and  a  terminal  rosette.  But  this  typical  body- 
form  he  saw  transformed  into  a  totally  different  one  in  which 
the  worms  "ganz  platt  und  am  beiden  Enden  gleich  sind"  (p. 
17).  (See  my  pi.  33,  figs.  1-4).  The  ordinary  frilled  form  he 
regards  as  a  contracted  condition  of  this  ' '  Ligulaa hnlicher " 
worm;  the  intermediate  stage  between  the  two  he  describes  as 
one  in  which  "die  Seitenrander  in  grossen  Wellen  gebogen  sind 
und  nur  der  ausserste  Teil  des  Trichters  in  einen  kleinen  krausen 


362          University  of  California  Publications  in  Zoology.     tv°L-  6 

Kopf  zusammengezogen. ' '  He  describes  also  a  third  contraction 
stage,  differing  from  the  ordinary  frilled  stage  even  more  widely 
than  the  *  *  Ligulaahnlicher. ' '  This  is  the  most  expanded  state 
of  the  worm,  described  by  Lonnberg  as  follows: 

"Wenn  der  Amphiptyches  sich  lebhafter  bewegen  will,  verlangert  er 
sein  Korper:  die  Querrunzeln  an  der  Mitte  des  Korpers  glatten  sich  aus, 
die  dichten  seitlichen  Krausen  wandeln  sich  dann  zuerst  in  weniger 
zahlreicher  Fallen  urn  und  diese  gehen  darauf  in  einige  wenige  grosse 
Wellen  iiber,  die  bald  auch  verschwinden  und  die  Seitenrander  glatt 
erscheinen  lassen.  Der  Korper  ist  nun  im  Ligulastadium,  also  platt  und 
lanzettenformig.  Aber  gleichzeitig  hiermit  vollziehen  sich  am  Trichter 
und  dem  Halsteil  grosse  Veranderungen.  Dieser  verliert  seine  seitlichen 
Fallen,  wird  langer  und  schmaler  und  erhalt  eine  cylindrische  Form. 
Jener  verlangert  sich  unverhaltnissmassig  mehr  und  zwar  in  der  Weise, 
dass  er  von  hinten  und  vorwarts  sich  in  ein  cylindrisches  Eohr  umwan- 
delt,  der  krause  'Kopf'  wird  immer  kleiner  und  gleichwie  vorwarts 
geschoben;  dies  geht  natiirlicher  Weise  so  zu,  dass  nach  un  nach  mehr 
von  den  proximalen  Teilen  des  Trichters  zur  Bildung  des  cylindrischen 
Eohres  angewandt  werden;  bald  sind  nur  die  aussersten  Lippen  ein  wenig 
kraus  und  schliesslich  werden  auch  diese  glatt  und  man  hat  eine  solche 
eigentiimliche  Form,  wie  fig.  36  [my  pi.  33,  fig.  2]  zeigt,  vor  sich. 

Bei  hochster  Ausdehnung  hat  dieser  Cylinder,  wie  oben 

geschrieben  ist,  beinahe  dieselbe  Lange  wie  der  ganze  iibrige  Korper, 
in  welchen  er  allmalig  ohne  Absatz  iibergeht.  Es  ist  mir  mit  schnell 
totenden  Eeagentien  gelungen  einige  Tiere  in  diesem  Stadium  zu 
fixieren,  und  wenn  ich  sie  mit  den  gewohnlichen,  krausen  Formen  ver- 
gleiche,  muss  ich  gestehen:  hatte  ich  nicht  selbst  mit  eigenen  Augen  die 
Umwandlungen  gesehen  und  die  Zwischenstadien  studieren  konnen,  so 
wiirde  es  mir  kaum  klar  werden  konnen  nur  zwei  verschiedene  Kontrak- 
tionszustande  vor  mir  zu  haben. "  (Lonnberg,  1891,  p.  17.) 

These  statements  of  Lonnberg 's  are  in  part  corroborated  by 
the  observations  of  Professor  Collett  (quoted  in  Lonnberg,  1891, 
p.  17,  footnote)  :  "Dass  zwei  verscheidene  Cestoden  die  Spiral- 
klappe  Chimaeras  bewohnte  und  zwar  ein  platter  Ligulaahn- 
licher und  der  gewohnliche  krause  Amphiptyches."  In  addi- 
tion Olsson  (1896)  reports  that  among  thirty-three  individuals 
he  found  "Deux  exemplaires,  longs  de  30mm,  avaient  la  forme 
curieuse  qui  a  ete  dessinee  par  Lonnberg  (1891,  fig.  36)  et  la 
conservent  encore  en  alcool.  La  longueur  du  cylindre  creux,  qui 
est  forme  du  cou  et  de  1'entonnoir,  est  de  pres  de  13mm,  celle 
du  corps  n'est  que  de  17  mm."  (See  Olsson 's  fig.  9,  p.  509). 

Braun  (1894)  gives  a  review  of  the  Cestodaria,  including 
Gyrocotyle,  He  recognizes  two  species  of  the  genus,  G.  urna 


1911]  Watson:  The  Genus  Gyrocotyle.  363 

(Gr.  et  Wag.)  (from  Chimaera  monstrosa)  and  G.  rugosa  Diesing 
(from  Callorhynchus  antarcticus) ,  but  adds  (p.  1157)  that  they 
"differiren  so  wenig  von  einander,  dass  es  fraglich  1st,  ob  die 
Unterscheidung  zweier  Species  sich  rechtfertigen  lasst^  moglich- 
erweise  bestehen  Unterscheide  in  der  Lage  der  Genitalpori. " 
According  to  Lonnberg  and  Wagener,  the  vaginal  opening  is  the 
most  anterior  and  lateral  to  the  penis ;  but  according  to  Spencer, 
dealing  with  G.  rugosa,  the  penis  opening  is  anterior  to  the 
vagina  and  marginal. 

Benham  (1891)  recognized  the  single  genus,  Gyrocotyle,  "in 
the  intestine  of  Chimaera  and  Callorhynchus." 

Haswell  (1902)  reported  a  new  species  of  Gyrocotyle,  G. 
nigrosetosa,  from  a  new  species  of  Chimaera,  C.  ogilbyi,  trawled 
off  the  Australian  coast  by  the  "Thetis."  Haswell  had  one 
specimen  of  G.  rugosa,  and  two  specimens  of  the  new  species, 
"not  in  good  condition  for  investigation."  He  did  not  study 
the  living  form.  He  distinguishes  G.  rugosa  from  G.  urna  (fol- 
lowing Lonnberg 's  description  of  the  latter)  on  the  following 
grounds : 

(1)  Relative   positions  of  the  apertures   of  the   penis  and 
vagina. 

(2)  Presence  of  an  eversible  cirrus,  adapted  to  self -impreg- 
nation, in  G.  rugosa. 

(3)  Spinules  lining  ejaculatory  duct,  in  G.  urna. 

(4)  Size  of  eggs. 

(5)  Presence  of  hexacanth  embryo  in  G.  rugosa. 

(6)  Shape  of  spines,  which  are  simpler  in  G.  rugosa. 

C.  GYROCOTYLE  OF  THE  COAST  OF  CALIFORNIA. 

I.    OCCURENCE    AND    HOST. 

As  this  review  of  the  literature  shows,  the  genus  Gyrocotyle 
includes  three  species,  G.  rugosa,  G.  urna,  and  G.  nigrosetosa^ 
all  occuring  as  intestinal  parasites  in  the  family  Chimaeridae. 
The  occurrence  of  a  form  of  the  genus  in  Chimaera  colliei,  found 
off  the  coast  of  California,  has  not  to  my  knowledge  been  previ- 
ously reported.  So  far  as  can  be  determined,  no  work  has  ever 
been  done  on  the  parasites  of  C.  colliei.  This  is  the  only  species 


364          University  of  California  Publications  in  Zoology.     [VOL.  6 

of  Chimaera  found  on  the  Pacific  coast  of  the  United  States 
(Dean,  1906,  pp.  6,  7)  and  was  first  described  by  Lay  and  Bennet, 
1839,  p.  71,  pi.  23,  in  Zoology  of  Captain  Beechey's  Voyage. 
Professor  Bashford  Dean  (1906)  bases  his  work  largely  on  eggs 
of  C.  colliei,  and  gives  a  description  of  the  living  fish,  with  notes 
on  its  occurrence,  habitat,  food  and  breeding  habits.  It  occurs 
in  depths  of  from  5  to  10  fathoms,  being  found  in  shallower 
water  in  the  Puget  Sound  region  than  along  the  California  coast. 
The  specimens  examined  by  the  writer  have  come  from  the  fishing 
grounds  oft3  Pifios  buoy  in  Monterey  Bay,  mentioned  by  Dean 
(1906,  p.  15)  ;  from  Cabral's  banks  off  San  Diego;  and  to  the 
north  of  San  Diego,  off  La  Jolla,  in  depths  up  to  fifty  fathoms. 
Dean's  observations  (1906,  p.  20)  on  the  food  habits  of  this 
species,  are  as  follows : 

"In  view  of  the  special  character  of  the  dentition  of  Chimaera,  one 
would  naturally  expect  its  food  supply  to  be  definite  in  character.  The 
examination  of  the  contents  of  its  gut,  however,  showed  (C.  colliei)  singu- 
larly omnivorous  habits.  It  is  true  that  the  broken  shells  of  mollusks 
are  commonly  found,  -as  well  as  fragments  of  good-sized  crustaceans,  as 
indeed  the  scanty  literature  records.  Thus,  in  the  gut  of  C.  monstrosa 
Faber  finds  Crustacea  and  shell-fish  fragments;  Monticelli,  quoting 
Liitken,  Cyprina  islandica;  and  Olsson,  broken  shells  (Leda  and  Venus) 
and  bits  of  large  decapods.  Olsson  finds  also  (and  his  observations  are 
the  most  detailed  hitherto  published  on  the  feeding  of  Chimaera)  chaeto- 
pods,  amphipods,  echinoids  and  polyps.  In  C.  colliei  observations  on 
about  a  score  of  individuals  showed  a  singular  mixture  of  foods.  The 
most  numerous  were  vertebral  columns  of  small  isospondylous  fishes,  a 
few  mollusk  shells,  usually  greatly  crushed,  a  quantity  of  sand  and  fine 
gravel,  squid,  nudibranchs  and  opisthobranchs,  bits  of  cases,  jaws  and 
setae  of  annelids,  and  occasionally  a  fragment  of  a  crustacean.  In  one 
instance  the  gut  was  filled  with  seaweed.  One  is  not  surprised,  there- 
fore, that  this  species  is  taken  readily  with  various  baits." 

The  observations  on  stomach  contents  made  by  Professor 
Kofoid  and  myself  yield  results  agreeing  in  general  with  the 
above;  with  the  addition  that  the  stomachs  contained  a  great 
quantity  of  echinoderm  spines,  plates,  etc.  Small  fish  were  com- 
mon, as  were  fragments  of  lamellibranchs,  nudibranchs  and  gas- 
teropods.  Cephalopod  beaks  were  almost  always  found.  Crus- 
tacean fragments,  especially  of  Hippa  and  Blepharada,  were  not 
uncommon  in  the  San  Diego  specimens.  The  fish  is  so  nearly 
omnivorous  in  food  habits  that  no  definite  clue  as  to  the  life- 
history  of  its  parasites  can  be  obtained  from  these  data. 


1911]  Watson:  The  Genus  Gyrocotyle.  365 

The  examination  of  C.  colliei  for  parasites  has  yielded  the 
following  results : 

(1)  The  fish  is  almost  invariably  infested  with  a  parasite 
belonging  to  the  genus  Gyrocotyle.     The  parasite  was- found  in 
34  of  the  38  specimens  examined. 

(2)  The  parasite  rarely  occurs  singly,  but  usually  two  indi- 
viduals in  one  host.     More  than  three  in  one  fish  I  have  never 
found.    In  four  cases  a  single  individual  was  found. 

(3)  No  other  adult  cestodes  have  been  found  in  the  alimen- 
tary tract  of  the  fish.     Encysted  cysticerci  are  common  in  the 
walls  of  the  tract,  in  the  mesenteries,  liver,  etc.,  especially  during 
the   summer  months.     Parasitic    crustaceans    were    frequently 
found  on  the  gills,  and  an  aspidocotylean,  probably  belonging  to 
the  genus  Macraspis,  was  found  embedded  in  the  muscles  of  the 
rectum.    A  distome,  bearing  a  strong  superficial  resemblance  to 
a  small  Gyrocotyle  without  frills,  was  found  once  in  the  posterior 
region  of  the  rectum,  and  once  in  the  body-cavity. 

(4)  Two  distinct  species  of  Gyrocotyle  are  found  in  C.  col- 
liei; one,  the  less  common  of  the  two,  is  closely  related  to  and 
perhaps  identical  with,   Gyrocotyle  urna;  the  other  differs  in 
several   characteristics   from   any   species   heretofore   described. 
The  incompleteness  of  the  figures  and  descriptions  of  G.  urna 
make  it  impossible  to  determine  accurately  the  identity  of  the 
form  first  mentioned  with  G.  urna.    It  will  be  referred  to  as  G. 
urna  (var.  ?) .    The  second  form,  which,  in  view  of  its  well-defined 
peculiarities  and  of  the  absence  of  any  intermediate  forms  link- 
ing it  to  any  described  form,  I  regard  as  a  new  species,  will  be 
refered  to  as  G.  fimbriata. 

Gyrocotyle  fimbriata,  sp.  nov. 

Diagnosis. — Color,  creamy  white ;  length  30-55  mm,  width 
7-12  mm.;  rosette  posterior,  folds  complex;  lateral  frills  3-5  mm. 
deep,  much  folded,  passing  into  smooth  lateral  fin  near  anterior 
extremity;  spines  numerous,  distributed  in  definite  pattern, 
points  directed  anteriorly;  eggs  about  0.09  mm.  in  average  long 
diameter,  no  hooked  embryos;  penis  opens  mediad  of  vagina,  at 
about  the  same  antero-posterior  level.  Occurs  in  spiral  valve  of 
Chimaera  colliei;  can  leave  host  and  live  for  some  days  free. 


366          University  of  California  Publications  in  Zoology.     [VOL-  6 

These  two  species  occur  in  fish  from  the  same  locality,  even 
taken  on  the  same  trawl.  Both  species  have  never  been  found  in 
the  same  individual.  G.  fimbriata  is  the  more  abundant  of  the 
two. 

II.  GROSS  ANATOMY  OF  GYROCOTYLE. 

The  characteristics  on  the  basis  of  which  species  are  separated, 
as  given  in  the  literature  of  the  genus,  are  of  various  degrees  of 
usefulness  and  trustworthiness.  This  is  due  in  great  measure 
to  the  manifold  changes  in  form  and  appearance  of  the  living 
animal  and  of  specimens  preserved  by  different  methods  in  all 
stages  of  contraction  and  deterioration.  Before  they  can  be 
intelligently  considered,  a  brief  description  of  the  gross  struc- 
ture of  the  animal  and  of  the  external  form  and  behavior  of  the 
living  specimen  will  be  necessary.  First,  the  orientation  adopted 
in  this  paper  must  be  defined.  The  pointed  acetabular  end  is 
the  anterior,  the  rosette  or  canal  end  the  posterior.  The  surface 
on  which  lie  the  uterine  pore  and  opening  of  the  canal  is  the 
creeping  surface  and  the  one  to  which  the  animal  returns  in  rest. 
It  is  therefore  ventral.  The  following  description  refers  espec- 
ially to  G.  fimbriata. 

The  worm  when  alive  and  attached  is  almost  translucent. 
After  detachment  it  becomes  opaque,  whitish-yellow  in  color, 
decidedly  deeper  in  tone  in  the  marginal  frills  and  the  folds  of 
the  terminal  posterior  rosette.  The  anterior  end  is  not  frilled,  is 
highly  contractile,  and  in  the  living  animal  is  in  constant  motion 
(pi.  33,  figs.  7-9).  It  consists  of  a  very  muscular  acetabulum, 
whose  margin  can  be  retracted  somewhat,  while  the  whole  can  be 
drawn  back  into  the  body  by  the  retraction  of  the  longitudinal 
muscles  attached  to  the  sucker.  Posterior  to  the  acetabulum,  in 
the  median  dorsal  line,  lies  the  opening  of  the  uterus  (ut.  po., 
pi.  39,  fig.  42).  Anterior  to  this,  one-third  of  the  distance  be- 
tween the  uterine  pore  and  the  posterior  margin  of  the  aceta- 
bulum, lie  the  vaginal  opening  (vag.  op.),  on  the  ventral  surface, 
and  the  penis  opening  (p.  op.),  on  the  dorsal  surface.  Both  lie 
almost  on  the  margin,  but  the  penis  opening  is  the  more  mediad 
and  anterior  to  the  vaginal  pore.  In  the  median  third  of  the 
body  of  the  adult,  the  much  coiled  and  distended  uterus  occupies 


1911]  Watson:  The  Genus  Gyrocotyle.  367 

most  of  the  space.  In  front  and  to  either  side  of  it,  running 
forward  to  the  posterior  margin  of  the  sucker,  are  the  follicles 
of  the  testes.  Peripheral  to  these,  running  out  into  the  lateral 
folds,  are  the  follicles  of  the  vitellaria,  distributed  from  the 
acetabular  region  to  the  base  of  the  posterior  rosette.  Along 
the  dorsal  surface  and  to  the  left  of  the  uterus  runs  the  vagina, 
leading  to  the  large  receptaculum  seminis  (rec.  sem.)  located 
just  posterior  to  the  uterus.  On  each  side  of  the  receptaculum 
seminis  lie  the  follicular  ovaries  (ovar.)  ;  immediately  in  front 
of  it  are  the  vitelline  ducts  (vit.  d.)  and  the  first  coils  of  the 
uterus.  The  shell-glands  (sh.  gl.)  are  found  around  these  ducts. 
It  is  in  this  region  that  the  ova  are  fertilized,  unite  with  the  yolk- 
cells  and  receive  their  shell-coating.  Behind  the  receptaculum 
seminis  and  the  ovaries  lies  the  ventral  opening  of  the  rosette 
canal.  This  structure  may  be  regarded  as  consisting  of  two 
parts.  The  first  is  a  flaring  " funnel,"  its  opening  terminal,  its 
margin  frilled  and  folded  till  it  resembles  a  carnation,  or  as  the 
Germans  put  it,  a  "Kohlkopf."  This  funnel  passes  directly 
acetabulad ;  it  leads  into  a  narrow  canal,  which  turns  at  almost  a 
right  angle  to  the  course  of  the  funnel,  passing  to  the  ventral 
surface  (pi.  34,  fig.  15).  This  ventral  opening  I  have  called  the 
" canal  opening"  (can.  op.,  pi.  46,  fig.  76),  in  distinction  from 
the  terminal  funnel  opening  above  described.  Funnel  and  canal 
together  are  called  by  German  workers  the  ' '  Trichter ' ' ;  Spencer 
speaks  of  the  funnel-margin  as  the  " rosette"  and  calls  the  canal 
opening  the  "proboscis." 

Gyrocotyle  fimbriata  (pi.  48,  figs.  80,  81),  while  bearing  a 
general  resemblance  to  the  described  species  of  the  genus,  differs 
markedly  in  certain  external  characteristics.  The  body  in  ex- 
panded condition  is  about  four  times  as  long  as  wide ;  the  lateral 
frills  never  totally  disappear  in  any  stage  of  expansion,  but  can 
be  distinguished  from  the  median  portion  of  the  body  under  all 
conditions.  They  are  about  one-fourth  the  total  width  of  the 
body  in  depth.  In  contracted  specimens  the  folds  of  the  two 
sides  are  invariably  drawn  toward  each  other  on  the  ventral 
(canal  opening)  surface.  The  posterior  terminal  rosette  (post, 
ros.,  pi.  34,  figs.  10,  12-15),  is  from  one-half  to  three-quarters  the 
greatest  width  of  the  body  in  transverse  diameter.  Its  depth  is 


368          University  of  California  Publications  in  Zoology.     [VOL-  6 

about  one-third  its  width,  and  its  dorso-ventral  diameter  varies 
from  one  to  one-half  the  transverse  diameter,  or  even,  in  excep- 
tional cases,  to  twice  this  diameter.  The  folds  of  the  rosette  are 
not  simple,  but  are  secondarily  folded,  standing  in  marked  con- 
trast to  the  lateral  folds,  which  consist  of  a  single  series  of  undu- 
lations. The  appearance  suggests  that  the  outer  wall  of  the  funnel 
is  more  contractile  than  the  inner,  the  result  being  the  production 
of  a  multitude  of  small  secondary  folds  on  the  inner  surface  of 
the  funnel.  The  gross  appearance  of  this  type  of  rosette  suggests 
a  finely  villous  surface,  such  as  an  intestinal  mucosa.  The  large 
folds  with  long  axis  parallel  to  the  long  axis  of  the  body,  so 
prominent  in  other  species,  are  almost  obliterated  here,  especially 
in  preserved  specimens. 

The  anterior  or  acetabular  extremity  (pi.  33,  figs.  7-9 ;  pi.  36, 
figs.  22,  23),  is  bluntly  pointed  and  bears  a  lateral  "fin"  of  tissue, 
to  a  point  about  half-way  to  its  tip.  The  acetabulum  (acet.)  is 
contractile  within  itself  to  a  high  degree  and  the  structure  as  a 
whole  can  be  drawn  back  into  the  body  by  the  strong  longitudinal 
muscles.  This  occurs  in  the  most  strongly  contracted  stage  (acet., 
pi.  34,  fig.  10).  The  body  is  markedly  asymmetrical,  owing  to  the 
formation  of  a  deep  "genital  notch"  in  the  left  margin  (gen. 
notch).  The  vaginal  opening  lies  at  the  angle  of  this  notch  on 
the  ventral  (canal  opening)  surface,  appearing  as  a  narrow  slit 
bounded  by  a  slightly  elevated  ring;  the  penis  opens  dorsally  in 
a  pit  at  the  base  of  a  very  low  and  inconspicuous  mound,  about 
two-thirds  of  the  distance  from  the  apex  of  the  notch  to  the 
median  line  (p.  op.,  pi.  36,  fig.  23).  The  relation  of  penis  to 
vagina  varies  within  narrow  limits,  but  in  general  they  may  be 
said  to  be  at  practically  the  same  antero-posterior  level. 

The  lateral  frills  extend  anteriorly  to  about  the  level  of  the 
genital  notch,  in  front  of  which  they  are  continued  as  the  un- 
f rilled  "lateral  fin"  above  mentioned.  Posteriorly  they  extend 
to  the  tip  of  the  posterior  rosette.  The  funnel,  whose  margin  is 
formed  by  the  posterior  rosette,  narrows  rapidly  to  a  small  canal, 
which  turns  at  an  angle  slightly  greater  than  90°,  and  opens  by  a 
small  aperture  on  the  ventral  (vaginal  opening)  surface  (can.  op., 
pi.  46,  fig.  76).  The  margin  of  the  aperture  is  raised  into  a  ring, 
and  is  crenate  (can.  op.,  pi.  34,  figs.  14,  15). 


Watson:  The  Genus  Gyrocotyle.  369 

Specimens  taken  from  decaying  fish  have  very  generally 
shown  a  marked  diminution  in  both  lateral  frills  and  terminal 
rosette.  Comparison  of  these  with  behavior  of  fresh  specimens 
kept  in  culture  media  shows  that  the  diminution  is  due  to  an 
actual  disintegration  of  tissue.  The  lateral  frills  are  cut  off  along 
a  perfectly  definite  line,  running  in  a  slightly  irregular  antero- 
posterior  course.  The  line  can  be  made  out  some  twenty-four 
hours  before  autotomy  actually  occurs.  In  every  case  where  a 
specimen  appears  to  have  no  lateral  frills  or  noticeably  reduced 
ones,  examination  shows  a  cut  edge,  along  which  the  frills  have 
dropped  off.  It  is  possible  that  Diesing's  original  figure  was 
taken  from  a  specimen  in  which  this  autotomy  had  taken  place. 
The  frills  of  the  terminal  rosette  do  not  appear  to  be  cut  off  in 
this  regular  fashion,  but  disintegrate  on  the  margins  only ;  ragged 
strings  of  tissue  will  be  found  attached  to  the  body  of  the  rosette. 
Most  of  the  reduction  in  the  size  of  the  rosette  in  decayed  speci- 
mens I  believe  to  be  due  to  intense  contraction  of  that  region, 
though  undoubtedly  accompanied  by  a  certain  amount  of  actual 
disintegration  of  tissue.  When  the  parasite  is  left  in  the  dead 
fish  over  twelve  hours,  at  ordinary  temperature,  this  decay  begins. 

The  spines  characteristic  of  this  genus  are  very  prominent  in 
G.  fimbriata.  Their  arrangement  is  in  a  constant  pattern,  char- 
acteristic of  this  species.  This  pattern  is  described  in  detail 
later,  under  the  discussion  of  the  cuticula,  but  its  general  outline 
will  be  given  here  also  for  the  sake  of  convenience.  In  the 
anterior  region,  borne  on  the  lateral  "fins"  above  mentioned,  are 
from  five  to  seven  rows  of  very  large  black  spines  (pi.  36,  figs.  22, 
23.)  They  are  borne  on  very  low  papillae.  There  are  about 
twenty-five  of  these  spines ;  they  vary  in  length,  the  more  anterior 
and  marginal  ones  being  in  general  the  larger.  Their  form  and 
structure  are  discussed  below,  in  connection  with  the  description 
of  the  cuticula. 

In  the  posterior  region  of  the  body,  the  spines  are  longer  than 
those  above  described.  They  are  borne  on  large  rounded  papillae. 
They  form  a  "collar"  (pi'.  34,  figs.  10,  12)  around  the  region  of 
the  body  between  the  funnel  opening  of  the  rosette  and  the  canal 
opening.  On  the  dorsal  surface,  no  spines  are  found  in  front  of 
this  collar,  which  does  not  extend  quite  to  the  level  of  the  canal 


370          University  of  California  Publications  in  Zoology.     [y°L-  6 

opening.  On  the  ventral  surface  a  line  of  scattered  spines 
streams  off  laterally  and  anteriorly  from  the  tips  of  this  semi- 
circle to  about  the  level  of  the  receptaculum  seminis.  No  spines 
are  found  on  the  lateral  frills.  The  arrangement  of  the  spines  on 
the  ventral  surface  (pi.  34,  fig.  10)  is  a  fairly  constant  one.  It 
is  of  interest  when  considered  in  connection  with  Lonnberg's 
(1891)  theory  of  the  formation  of  the  funnel  and  canal  by  means 
of  the  partial  fusion  of  folds  of  the  ventral  body  wall. 

Gyrocotyle  urna  (Wagener)  var.? 

In  the  material  collected  by  Dr.  Kof oid  near  Monterey,  off  the 
California  coast  in  1904,  were  found  three  specimens  differing 
from  the  rest  in  certain  characters  which  seem  to  constitute  a 
basis  for  specific  distinction.  Later,  in  1907-1908,  the  writer 
found  several  similar  specimens.  The  characters  peculiar  to  this 
form  are  as  follows: 

1.  The  lateral  frills  are  less  voluminous. 

2.  The  folds  of  the   posterior  rosette   are  simple    (i.e.,  not 
thrown  into  irregular  secondary  frills,  as  in  G.  fimbriata),  vary- 
ing in  diameter  from  one-sixth  to  one-third  of  the  width  of  the 
body. 

3.  The  lateral  frills  do  not  extend  to  the  base  of  the  rosette 
but  taper  off  gradually,  disappearing  posterior  to  the  recepta- 
culum seminis. 

4.  Spines  are  present  over  the  whole  of  the  ventral  surface 
as  far  forward  as  the  middle  of  the  length  of  the  uterus,  and 
extend  thence  in  two  lateral  wings  forward  to  a  point  just  back 
of  the  level  of  the  opening  of  the  uterus.     There  is  no  distinct 
pattern  discernible  as  in  G.  fimbriata.     There  are  only  a  few 
scattered    spines    on    the    dorsal    surface,    except    around    the 
"collar,"  immediately  in  front  of  the  base  of  the  frill  of  the 
posterior  rosette. 

5.  The  relative  position  of  the  opening  of  the  penis,  uterus, 
and  vagina  is  markedly  different  from  that  seen  in  G.  fimbriata. 
(See  measurements,  p.  381.) 

Except  in  two  particulars,  i.e.,  the  distribution  of  the  spines 
and  the  fact  that  penis  and  vagina  open  at  approximately  the 
same  antero-posterior  level,  this  form  seems  to  be  identical  with 


1911]  Watson:  The  Genus  Gyrocotyle.  371 

Gyrocotyle  urna  as  described  by  Wagener  and  Lonnberg.  The 
distribution  of  spines  may  vary  with  age,  though  it  has  been 
found  constant  in  specimens  of  all  sizes  of  G.  fimbriata.  It  is 
also  possible  that  the  non-appearance  of  the  spines  may  be  due 
to  action  of  reagents  on  preserved  material.  The  figure  given  by 
Wagener  (1852)  shows  a  very  close  approach  to  the  pattern  given 
above  as  characteristic  for  G.  fimbriata.  The  whole  question  of 
distribution  of  spines  cannot  be  settled  until  more  material  is 
available. 

The  question  whether  penis  or  vagina  opens  more  anteriorly 
is  a  difficult  one.  In  specimens  killed  between  glass  plates,  these 
relations  can  be  very  easily  distorted.  On  the  other  hand,  in 
specimens  not  killed  thus,  it  is  very  difficult  to  compare  the  posi- 
tions of  the  two  openings,  as  they  are  on  opposite  surfaces  of  a 
body  too  thick  to  be  made  transparent  by  clearing  agents.  The 
specimens  in  my  possession  show  the  two  openings  at  practically 
the  same  level,  with  a  small  range  of  individual  variation,  depend- 
ing upon  the  degree  of  extrusion  of  the  penis-papilla. 

Not  having  specimens  of  G.  urna  for  comparison,  it  has  been 
impossible  to  decide  whether  this  form  is  really  a  distinct  one,  or 
belongs  to  Wagener 's  species.  Until  comparison  can  be  made,  it 
will  be  referred  to  as  G.  urna  (var.  ?). 

III.  BEHAVIOR  OF  THE  LIVING  ANIMAL. 

The  shape  of  the  body  varies  greatly  in  the  living  animal,  and 
also  in  preserved  specimens.  Wagener 's  figures  (pi.  48,  figs.  84, 
85)  are  the  best  in  the  literature,  so  far  as  giving  a  faithful  re- 
production of  the  appearance  of  the  living  worm.  His  figure  of 
the  preserved  specimen,  on  the  other  hand,  resembles  very  slightly 
any  specimen  that  has  come  under  the  writer's  notice.  The 
acetabular  extremity  of  the  living  animal  is  extended  into  a  long, 
slender,  cylindrical  proboscis,  along  the  sides  of  which  the  spines 
above  referred  to  are  distributed.  This  part  of  the  worm  is  in 
constant  motion.  Posterior  to  the  genital  openings,  in  the  region 
of  the  lateral  frills,  the  body  is  flattened,  slightly  convex  dorsally. 
Posterior  to  the  uterus  the  lateral  frills  become  less  deep,  and  the 
body  less  flattened.  This  "  neck ' '  region  can  be  very  considerably 
extended.  On  the  posterior  extremity  is  borne  the  rosette,  of 


372          University  of  California  Publications  in  Zoology.     [V°L.  6 

greater  size  in  G.  fimbriata  than  in  G.  urna,  and  its  folds  many 
times  as  complex,  but  generally  held  in  a  position  exactly  like  that 
shown  in  Wagener's  second  figure,  that  is,  the  opening  of  the 
funnel,  the  rosette  surface,  lying,  not  at  right  angles  to  the  sur- 
face of  the  body,  but  parallel  to  it. 

The  .stage  shown  in  Wagener  's  first  figure  represents  the  most 
extreme  stage  of  expansion  noted  by  the  writer.  No  stages  corre- 
sponding to  those  figured  by  Lonnberg  (pi.  33,  figs.  1-4)  were 
seen,  although  the  specimens  observed  were  in  many  cases  per- 
fectly fresh  and  very  active,  contracting  and  expanding  with 
great  freedom,  and  moving  about  in  the  dish.  But  the  shape  of 
the  posterior  rosette  was  never  materially  altered,  nor  did  the 
lateral  folds  completely  disappear.  Further,  in  the  observations 
by  Wagener,  by  Dr.  Kofoid,  and  by  the  writer  on  the  worm,  an 
expanded  condition  always  involves  expansion  of  the  acetabular 
extremity  as  well  as  the  neck  of  the  rosette.  None  of  Lonnberg 's 
figures  shows  anything  suggesting  the  very  characteristic  aceta- 
bular extremity  as  first  figured  by  Wagener.  In  observations  of 
twenty-three  living  worms  the  writer  has  never  failed  to  find  the 
acetabular  extremity  assuming  and  maintaining  this  appearance 
throughout  the  period  of  activity.  Lonnberg 's  observations,  as 
above  noted,  are  corroborated  by  Olsson  (1896),  who  adds  the 
astonishing  statement  that  the  worms  preserve  this  form  in 
alcohol.  As  the  parasite  is  exceedingly  sensitive  to  chemical 
stimuli,  and  invariably  reacts  to  even  a  very  dilute  solution  (5 
per  cent.)  of  alcohol  by  strong  contraction,  this  seems  to  indicate 
that  Olsson  at  least  was  dealing  with  some  form  other  than 
Gyrocotyle.  The  writer  found  on  two  occasions,  while  searching 
for  Gyrocotyle  in  Chimaera  colliei,  a  distome  strongly  suggesting 
Lonnberg 's  figure  and  maintaining  its  shape  in  killing  fluids, 
which  might  have  been  mistaken  for  Gyrocotyle.  But  since  Lonn- 
berg states  explicitly  that  these  transformations  in  form  took 
place  under  his  eyes,  this  explanation  seems  scarcely  possible. 
We  are  forced  to  accept  a  discrepancy  in  results  here,  only  to  be 
removed  by  further  investigation. 

The  living  worm,  in  the  intestine  of  a  fish  that  has  just  been 
caught,  is  translucent,  of  a  dull  pink  color,  exactly  similar  to 
the  intestine  on  which  it  lies.  The  worm  in  perfectly  fresh  fish 


1911]  Watson:   The  Genus  Gyrocotyle.  373 

is  firmly  attached  by  the  terminal  rosette,  which  is  spread  over 
an  area  of  ten  to  twelve  millimeters  in  diameter.  The  folds  of  the 
rosette  fit  over  the  vi.lli  of  the  intestine.  The  canal  opening  (on 
the  ventral  surface)  is  closed  as  long  as  the  rose tte_ remains 
attached.  A  series  of  waves  of  contraction  passes  from  the 
margin  of  the  rosette  toward  the  canal  opening,  during  the 
attachment  of  the  rosette.  The  lateral  frills  are  present  even  in 
the  most  expanded  state  of  the  worm,  constituting  one-half  of 
the  total  width  of  the  body.  The  acetabulum  is  very  active, 
thrusting  itself  backward,  under,  over  or  to  the  side  of  the  body. 
The  whole  worm  contracts  and  expands  frequently  without  any 
apparent  stimulus.  The  parasite  is  not  easily  affected  by 
mechanical  stimuli  under  these  conditions,  but  will  contract  if 
exposed  to  direct  sunlight,  and  is  very  sensitive  to  chemical 
stimuli.  The  acetabulum  has  never  been  found  attached,  or  in 
any  sense  functioning  as  a  sucker.  This  statement  is  borne  out 
by  all  investigators. 

Shortly  after  the  death  of  the  fish,  the  fluid  intestinal  con- 
tents become  thick  and  opaque,  and  the  worm  detaches  itself  and 
contracts,  losing  its  translucence  and  becoming  creamy-white  in 
color.  The  region  of  the  mucous  membrane  to  which  the  rosette 
has  been  attached  is  of  a  deep  purplish  red,  and  appears  inflamed 
after  the  rosette  has  detached  itself.  Many  of  the  worms  are 
found  in  this  opaque  condition,  and  do  not  again  become  active. 
From  observations  on  the  behavior  of  the  attached  specimens,  and 
from  the  fact  that  inactive  specimens  are  found  in  all  parts  of 
the  intestinal  tract,  in  the  mouth  and  on  the  gills,  it  appears 
fairly  certain  that  the  worm  attempts  to  leave  the  dead  host,  and 
very  frequently  succeeds  in  doing  so.  In  one  case,  the  worm  was 
found  crawling  up  the  first  turn  of  the  valve,  when  the  intestine 
was  opened.  The  fact  that  specimens  are  so  often  found,,  either 
in  the  first  or  next  to  the  last  turn  of  the  valve,  also  points  to  this 
conclusion.  Finally,  the  finding  of  a  living  specimen  crawling 
on  the  bottom  of  a  jar  of  sea-water  in  which  a  Chimaera  had 
been  placed,  is  fairly  conclusive  evidence  that  the  worm  occa- 
sionally succeeds  in  escaping  from  its  host.  The  parasite  is  never 
found  attached  elsewhere  than  in  the  spiral  valve.  Spencer 
(1889,  p.  138)  remarks  in  this  connection:  "The  specimens 


374          University  of  California  Publications  in  Zoology.     [VOL.  6 

[of  Gyrocotyle  rugosa]  obtained  by  myself — three  in  number — 
were  taken  from  the  mouth  of  Callorhynchus  antarcticus,  and 
their  presence  in  such  a  position  was  doubtless  associated  with 
the  fact  that  the  fish  had  been  dead  some  twenty-four  hours, 
though  the  parasites  were  still  living  and  evidently  trying  to  find 
their  way  out  of  the  dead  body."  Wagener  (1852,  p.  543)  says: 
"Nur  einmal  fand  es  sich  an  den  Kiemen,  wobei  jedoch  bemerkt 
werden  muss,  dass  die  Fisch  schon  12  Stunden  ausserhalb  des 
Wassers  sich  befand."  Lonnberg  (1891)  mentions  the  finding  of 
G.  urna  living  free,  but  supposes  the  worms  to  have  finished 
their  cycle  and  to  have  been  cast  out  with  the  excrement  of  the 
host.  He  seems  to  imply  in  the  following  statement  that  the 
worms  leave  the  dead  host  (writing  of  the  almost  invariable 
occurrence  of  the  parasite  in  Chimaera)  :  ''In  zwei  anderen,  die 
ich  in  Upsala  untersuchte,  die  aber  von  Trondhjem  stammten, 
habe  ich  ihn  nicht  gefunden,  aber  diese  Fische  waren  schon  seit 
mehreren  Tagen  ausserhalb  des  Wassers."  It  may  then  be  re- 
garded as  an  established  fact  that  the  parasite  is  capable  of  a 
very  considerable  amount  of  locomotion,  and  that  it  can,  under 
favorable  conditions,  leave  its. host  and  live  for  some  days  outside 
the  intestinal  tract.  The  most  important  condition  seems  to  be 
temperature;  a  low  temperature  (about  10°-12°  C.)  is  most 
favorable.  In  warm  weather  the  worms  remain  active  for  only 
a  very  short  time,  and  have  never  succeeded  in  getting  out  of 
the  intestine  in  any  case  under  my  observation.  This  ability 
to  leave  the  host,  taken  in  connection  with  the  behavior  of  the 
isolated  parasite  as  described  below,  has  an  important  bearing 
both  on  the  problem  of  orientation  and  on  the  question  of  the 
habitat  of  the  parasite,  which  will  be  discussed  later. 

The  worms  on  being  removed  from  the  fish  were  placed  in 
culture  fluids.  The  worm  is  very  active,  if  removed  soon  after 
the  death  of  the  fish  and  kept  at  a  low  temperature.  The  culture 
solution  quickly  becomes  contaminated  with  bacteria,  and  the 
worm  contracts  and  grows  sluggish.  When  changed  to  fresh 
solution  the  parasite  expands  and  renews  its  movements.  These 
consist  of  the  following : 

1.  Thrusting  and  exploring  movements  of  the  acetabular  ex- 
tremity, accompanied  by  contraction  and  expansion  of  the  body. 


1911]  Watson:  The  Genus  Gyrocotyle.  375 

2.  "  Kighting-up  "  movements,  in  which  the  worm  turns  from 
one  surface  to  the  other.     These  take  place  when  the  worm  is 
placed  on  its  dorsal- surf  ace  and  also  when  it  is  exposed  to  strong 
light. 

3.  This  turning  over  is  accomplished  in  two  typical  ways, 
either  by  turning  completely  over  on  one  side  on  the  frills  as  an 
axis,  or  by  a  more  elaborate  process  of  tucking  under  the  aceta- 
bulum  until  it  emerges  posterior  to  the  rosette,  when  the  rosette 
is  elevated  and  the  overturning  accomplished  after  the  manner  of 
a  somersault. 

4.  A  rotation  from  side  to  side  of  the  terminal  rosette,  accom- 
panied by  a  wave-motion  in  the  margin  of  the  frills,  takes  place 
during  the  worm's  most  active  period. 

5.  Locomotion  in  a  definite  direction  is  accomplished  by  means 
of  a  series  of  expansions  and  contractions,  with  some  help  from 
the  mobile  lateral  frills.     The  acetabular  extremity  is  in  every 
case  directed  anteriorly;  the  rosette  is  held  in  the  typical  posi- 
tion, raised,  with  the  canal  opening  ventral  and  the  funnel  open- 
ing dorsal.     The  acetabulum  is  thrust  out,  and  the  whole  body 
elongates,    the    rosette   remaining    stationary.      This   expansion 
leaves  the  rosette  end  where  it  was  before,  the  acetabular  end 
some  two  centimeters  further  toward  the   goal  than   at  start. 
Then  a  wave  of  contraction  sets  in,  bringing  the  rosette  end 
nearer  the  acetabular  end,  which  also  moves  backward  a  short 
distance,  approaching  the  rosette.     The  net  result  is  an  advance 
in  the  acetabular  direction.    The  acetabulum  remains  contracted, 
while  the  rest  of  the  body  expands.    In  this  expansion  the  rosette 
must  either  retreat,  or  the  whole  contracted  anterior  extremity 
be  shoved  forward.    The  latter  is  what  actually  occurs,  as  shown 
by  careful  marking  of  the  relative  positions  of  the  two  ends 
before  and  after  the  wave  of  expansion.     This  method  of  pro- 
cedure is  very  effective,  resulting  in  an  average  gain  of  about 
two  centimeters  for  each  wave  of  contraction.     A  distance  of 
fourteen  centimeters  was  traveled  in  ten  minutes  by  one  speci- 
men ;  but  in  this  case  more  than  the  average  gain  was  made,  the 
whole  distance  being  accomplished  in  five  contractions. 


376          University  of  Calif ornia  Publications  in  Zoology.     [VOL.  6 

IV.  CHARACTERISTICS  FOR  SEPARATION  OF  SPECIES. 

The  characteristic  peculiarities  of  each  species  have  been  set 
forth  by  its  discoverer,  but  there  has  been  no  systematic  attempt 
to  assess  the  worth  of  these  characteristics  for  the  genus  as  a 
whole  since  that  of  Braun  (1894).  He  was  not  acquainted  with 
at  least  one  very  important  set  of  species  characteristics,  that 
proposed  by  Haswell  (1902). 

The  first  species  characteristics  were  proposed  by  Diesing 
(1859).  He  distinguishes  G.  rugosa  from  G.  urna  by  the  pres- 
ence of  lateral  frills  and  spines  and  the  greater  size  of  the  tail 
rosette  in  that  species. 

Monticelli  also  recognizes  these  two  species,  separating  them 
by  the  following  points : 

1.  The  absence  in  G.  rugosa  of  the  frilled  lateral  margins. 

2.  The  greater  length  of  the  uterus  in  G.  rugosa,  possibly  cor- 
related with  the  following  character. 

3.  The  presence  of  hooks  in  the  embryo  within  the  uterus  of 
G.  rugosa. 

Braun  (1894)  recognized  G.  urna  and  G.  rugosa,  but  only  as 
doubtfully  distinct.  The  basis  for  separation  he  finds  in  the 
position  of  the  opening  of  the  vagina  and  penis;  the  former 
being  the  more  anterior  in  G.  urna,  the  latter  in  G.  rugosa. 

Haswell  (1902)  recognized  G.  urna  and  G.  rugosa  and  tenta- 
tively proposed  a  new  species,  G.  nigrosetosa.  He  distinguished 
G.  rugosa  from  G.  urna  on  the  following  grounds : 

1.  Relative  position  of  the  apertures  of  penis  and  vagina. 

2.  Presence  of  an  eversible  cirrus  adapted  to  self-impregna- 
tion in  G.  rugosa. 

3.  Spinules  lining  the  ejaculatory  duct  in  G.  urna. 

4.  Presence  of  hexacanth  embryo  in  the  uterine  egg  of  G. 
rugosa. 

5.  Shape  of  spines. 

G.  nigrosetosa  he  distinguishes  on  the  following  grounds : 

1.  Size  of  eggs,  0.08  mm.,  as  distinct  from  eggs  of  G.  rugosa, 
0.1  mm. 

2.  Presence  of  operculum,  distinct  from  G.  rugosa  and  G. 
urna. 


1911 J  Watson:  The  Genus  Gyrocotylc.  377 

3.  Absence  of  hooked  embryos. 

After  careful  comparison  of  the  available  figures  and  descrip- 
tions and  a  study  of  about  forty  specimens,  ranging  in  state  of 
preservation  from  those  perfectly  fresh,  attached  to  the_ intestine 
of  the  host,  down  to  badly  disintegrated  specimens  from  various 
regions  of  the  alimentary  tract  of  decomposing  hosts,  the  writer 
has  found  certain  of  these  proposed  criteria  to  be  useful  and 
valid.  Certain  others  seem  untrustworthy.  These  specific  char- 
acters may  be  listed  and  criticized  as  follows : 

1.  Presence   of  lateral  frills. — It   seems   fairly   certain   that 
lateral  frills  are  present  in  all  species  of  the  genus,  when  the 
specimen  is  in  a  good  state  of  preservation.    Presence  of  the  frills 
is  therefore  not  a  basis  for  specific  distinctions.     The  amplitude 
of  the  frills,  and  their  relative  width   (in  terms  of  total  body 
width)  for  any  given  state  of  contraction  or  expansion,  is  how- 
ever a  characteristic  of  real  value  in  the  recognition  of  species. 
G.  rugosa  (pi.  38,  fig.  36)  has  comparatively  scanty  and  narrow 
frills ;  in  G.  nigrosetosa  the  frills  are  deeper  and  more  volu- 
minous; in  G.  urna  (pi.  47,  figs.  84,  85)  they  are  twice  the  depth 
of  those  in  G.  nigrosetosa  and  many  times  as  voluminous.     In 
G.  fimbriata  (pi.  34,  fig.  10)  they  are  still  more  ample  and  about 
the  same  depth  as  in  G.  urna.     While  these  differences  can  be 
easily  seen,  the  extreme  contractility  of  the  animal  makes  it  im- 
practicable to  attempt  to  use  this  characteristic  as  a  basis  for 
separation  of  species.    It  is  a  concomitant,  rather  than  a  critical 
characteristic,  not  available  for  exact  description. 

Diesing's  specimen  without  frills  was  taken,  it  will  be  recalled, 
from  Mactra.  According  to  the  best  of  our  knowledge  the  only 
host  of  the  adult  parasite  is  some  member  of  the  family  Chimaer- 
idae;  this  specimen,  having-  been  set  free  from  its  host  in  some 
fashion,  probably  entered  the  shell  of  the  mollusk  by  accident. 
Certainly  not  adapted  to  life  as  an  ectoparasite,  processes  of 
disintegration  would  undoubtedly  speedily  set  in,  and  my  own 
experiments  with  Gyrocotyle  in  culture  media  show  that  dete- 
rioration invariably  begins  by  cutting  off  of  the  lateral  frills  in 
increasingly  deeper  layers. 

2.  Presence  of  spines. — This  is  critical  only  when  applied  to 
living  specimens  and  to  those  which  have  been  preserved  in  such 


378          University  of  California  Publication*  in  Zoology.     tv°L-  6 

a  manner  as  not  to  injure  the  spines.  In  addition  to  the  effect  of 
reagents,  disintegration  results  in  the  early  loosening  and  dis- 
appearance of  the  spines.  In  no  case  where  the  living  worm  has 
been  examined  have  the  spines  been  absent. 

The  distribution  of  the  spines  affords  a  useful  basis  of  dis- 
tinction. In  G.  rugosa  (Spencer,  1889),  "spines  are  scattered 
over  the  whole  surface  of  the  body";  in  G.  nigrosetosa  (Haswell, 
1902)  "they  are  mainly  confined  to  the  dorsal  surface,  except  at 
the  anterior  end.  Over  the  rest  of  the  ventral  surface  are 
scattered  a  very  few,  much  smaller  than  those  on  the  dorsal  sur- 
face." In  G.  urna  (Lonnberg,  1891),  the  distribution  is  confined 
to  the  extremities  and  the  lateral  margins  of  the  body,  leaving 
the  middle  of  the  body,  from  just  in  front  of  the  canal  opening 
to  the  level  of  the  acetabulum,  free  from  spines.  In  G.  fimbriata 
the  condition  is  as  described  by  Lonnberg  for  G.  urna,  except 
that  spines  are  absent  from  the  greater  part  of  the  lateral  margin 
of  the  body,  and  do  not  occur  on  the  lateral  frills.  Possible 
variation  with  age  and  the  ease  with  which  spines  may  be  lost 
by  slight  disintegration  or  action  of  reagents,  makes  any  dis- 
tinction resting  on  them  somewhat  impracticable.  Here  again 
we  have  differences  coordinated  with,  but  scarcely  useful  as, 
specific  distinctions. 

3.  Size  of  tail  rosette. — This  character  appears  to  depend  less 
on  the  state  of  contraction  than  do  the  width  and  amplitude  of 
the  lateral  folds,  and  if  reduced  to  a  definite  statement  in  terms 
of  some  other  dimension  of  the  animal,  would  probably  be  found 
to   vary   about   a   mean   characteristic   for   each   species.      The 
astonishing  illustrations  given  by  Lonnberg   (pi.  33,  figs.   1-4) 
would,  if  corroborated,  not  necessarily  invalidate  the  worth  of 
this   characteristic,   provided   comparisons   were   made   between 
specimens  in  a  similar  state  of  contraction,    G.  rugosa  (pi.  33, 
figs.  5,  6)  in  a  contracted  state  has  a  rosette  about  one-fourth  its 
greatest  body-width  in  diameter.     In  G.  nigrosetosa,  the  rosette 
is  about  five-sixths  the  body- width;  in  G.  urna  about  one-half; 
while  in  G.  fimbriata  it  varies  from  two-thirds  to  three-fourths 
or  even  more. 

4.  Length  of  uterus. — This  is  a  character  which  it  is  exceed- 
ingly  difficult   to   apply.      The   length   of   the   much-contorted 


1911]  Watson:   The  Genus  Gyrocotyle.  379 

uterus  is  hard  to  estimate,  the  number  of  turns  may  vary  with 
the  state  of  contraction,  and  certainly  varies  with  age.  I  have 
been  unable  to  reduce  this  to  definite  measurements.  From 
Spencer's  diagram  it  seems  probable  that  the  uterus  occupies 
more  space  in  G.  rugosa  than  it  does  in  G.  fimbriata,  or,  accord- 
ing to  Haswell,  in  G.  nigrosetosa. 

5.  Presence  of  hooked  embryos  in  uterine  eggs. — This  is  a 
character  easily  applied  and  apparently  thoroughly  critical.     It 
serves  to  set  off  G.  rugosa  from  the  rest  of  the  genus. 

6.  The  relative  positions  of  the  openings  of  the  penis  and 
vagina. — This  character  is  perfectly  definite  and,  applied  to  ma- 
terial not  flattened  under  pressure  when  killed,  seems  trustworthy. 
There  is  one  possible  source  of  confusion,  in  the  fact  that  the  penis 
opening  is  on  the  summit  of  a  papilla,  very  mobile  and  capable 
of  considerable  extension.     The  vagina  is  fixed  in  position.     In 
case  this  papilla  should  be  fully  extended,  the  penis  opening 
might  lie  in  front  of  the  vagina ;  while  if  withdrawn  it  would  lie 
well  behind  it.     The  same  criticism  might  hold  for  medio-lateral 
relations.     The  fact  that  G.  rugosa,  the  only  form  in  which  the 
penis  papilla  has  been  observed  greatly  extruded,  is  also  the  only 
one  in  which  the  opening  is  definitely  in  front  of  the  vaginal 
opening,  suggested  this  possible  source  of  error.    Spencer's  figure 
seems  to  point  in  this  direction. 

7.  Presence  of  an  eversible  cirrus,  adapted  to  self-impregna- 
tion.— This  arrangement  has  been  reported  only  by  Haswell  for 
G.  nigrosetosa.    It  does  not  seem  probable  that  only  one  species 
of  the  genus  possesses  a  type  of  cirrus  adapted  to  self-impregna- 
tion, especially  when  it  is  reflected  that  single  individuals  of  all 
reported  species  have  been  found  repeatedly  in  their  hosts.     It 
is  strange  that  no  eversion  of  the  cirrus  has  ever  been  noted  in 
any  except  the  one  specimen  of  G.  rugosa  studied  by  Haswell, 
and  possibly  in  the  one  figured  by  Spencer. 

8. — Spinules  lining  ejaculatory  duct. — This  character  is  of 
service  in  setting  off  G.  rugosa  from  the  rest  of  the  genus; 
spinules  (interpreted  by  Lonnberg  as  cilia)  have  been  observed 
in  the  ejaculatory  duct  of  G.  nigrosetosa  by  Haswell,  of  G.  urna 
by  Lonnberg,  and  in  G.  fimbriata  by  the  writer. 

9.  Shape  of  spines. — The  data  on  this  point  need  revision. 


380          University  of  California  Publications  in  Zoology.     [VOL.  6 

The  shape  of  the  spines  may  vary  somewhat  in  different  regions 
of  the  same  animal.  Furthermore,  all  the  spines  thus  far  de- 
scribed correspond  exactly  to  those  figured  by  Lonnberg,  with 
the  exception  of  Spencer's  figure  of  the  spines  of  G.  rugosa. 
Possibly  a  study  of  more  individuals  of  the  latter  species  may 
show  closer  similarity  to  the  type  of  the  genus. 

10.  Size  of  eggs. — This  character  must  be  regarded  with  some 
distrust,  in  view  of  the  fact  that  one  individual  may  yield  ripe 
eggs  varying  in  size  from  0.075  mm.  to  0.115  mm. 

11.  Presence    of   an    operculum   in   the    egg-shell. — Haswell 
(1902)   figures  an  egg  of  G.  nigrosetosa,  having  a  thick  shell, 
with  a  thin  plate  at  one  pole,  in  diameter  less  than  one-third  the 
greatest  transverse  diameter  of  the  egg  (see  my  plate  47,  figure 
81.)     "A  circular  area  of  the  shell  at  one  pole  is  much  thinner 
than  the  rest,  and  is  probably  differentiated  as  an  operculum." 
The  same  observer  studied  eggs  of  G.  rugosa,  and  states  that  in 
them  the  shell  does  not  appear  to  be  provided  with  an  operculum. 
The  eggs  of  G.  fimbriata  show  when  discharged  no  such  thin  plate ; 
but  eggs  taken  from  poorly  preserved  specimens  show  an  oper- 
culum, its  diameter  a  little  more  than  half  the  greatest  transverse 
diameter  of  the  egg,  in  which  the  shell  is  slightly  thinner  than 
elsewhere.     Its  margin  is   serrated.     This   cap   differs   in   size, 
thickness,  and  character  of  margin  from  the  operculum  of  Has- 
well, but  seems  to  be  an  homologous  structure.     The  significant 
point  is  that  there  is  no  trace  of  it  in  the  freshly  discharged  ova, 
and  that  it  does  appear  very  clearly  later.     Probably  the  ova 
of  G.  urna  and  G.  rugosa  would  also  show  a  similar  structure, 
at  a  similar  stage.     The  problem  is  whether   Haswell's   oper- 
culum is  present  in  a  freshly  discharged  or  intra-uterine  egg,  or 
whether  it  is  merely  an  early  stage  of  the  formation  of  this  cap. 
Only  in  the   former  case  does  the  operculum  become  a   good 
specific  character.     Haswell  explicitly  observes  that  "the  speci- 
mens were  not  in  good  condition  for  minute  investigation."    His 
figure  (see  my  plate  47,  figure  80)  shows  the  neck  of  the  rosette 
as  swollen,  recalling  an  appearance  characteristic  of  worms  kept 
too  long  in  culture  media.     But  in  the  absence  of  any  definite 
statement  as  to  the  condition  of  the  two  specimens  of  G.  nigro- 


19111  Watson:   The  Genus  Gyrocotyle.  381 

setosa,  the  presence  of  an  operculum  in  uterine  eggs  must  be 
adopted  as  a  specific  characteristic  of  G.  nigrosetosa. 

In  addition  to  these  characters  which  have  been  proposed  and 
found  trustworthy,  the  writer  suggests  the  following: 

1.  The  character  of  the  folds  of  the  terminal  rosette,  whether 
simple  or  complex.     This  is  correlated  with  the  greater  relative 
size  of  the  rosette ;  but  the  fact  that  the  size  varies  greatly  and  is 
difficult  to  express  in  a  ratio  that  could  be  applied  to  any  speci- 
men to  be  determined,  makes  the  character  of  the  folds  them- 
selves seem  a  more  easily  applicable  test.    The  writer  is  convinced 
that  this  character  is  constant  in  all  stages  of  contraction,  at  all 
ages,  and  after  treatment  with  all  the  ordinary  reagents.     It 
becomes  unrecognizable  only  after  decay  has  proceeded  very  far 
indeed. 

2.  The  ratio  between  the  distance  from  the  opening  of  the 
uterus  to  the  tip  of  the  acetabulum,  and  the  distance  from  the 
opening  of  the  uterus  to  the  level  of  the  opening  of  the  penis. 
While  these  absolute  distances  vary  enormously  with  the  state  of 
contraction,  a  series  of  measurements  shows  that  the  ratio  is 
fairly  constant  about  a  mean  characteristic  of  the  species. 

TABLE  I. 
Eatios  of  Measurements  of  Position  of  Genital  Pores  in  Gyrocotyle. 

G.  Jimbriata  G.  urna  G.  rugosa        G.  urna  (Wag.)     G.  nigrosetosa 

.4615  .266  .515  .333  .490 

.4500  .222  .582 

.4444  .200  .592 

.4444  .200 

.4375 
.4375 
.4295 
.4295 
.4295 
.4290 
.4000 
.4000 
.3809 
.3333 
.3333 
.3333 


382         University  of  California  Publications  in  Zoology.     [VOL.  6 

V.  KEY   TO   SPECIES   OF    GYBOCOTYLE. 

On  the  basis  of  the  above  discussion,  the  following  classifica- 
tion is  proposed : 

A.  Frills  of  posterior  rosette  simple. 

I.  Uterine    eggs    containing    hooked    embryos.      Opening    of    penis 

laterad  of,  and  anterior  to,  vaginal  opening. 

G.  rugosa. 

Host:  Mactra  edulis.  Diesing  (1850,  p.  408)  Brazil.  Mon- 
ticelli  (1889b,  p.  228). 

Callorhyncus   antarcticus.      Monticelli    (1889c,   p.    327), 
Dunedin,  N.  Z.     Spencer  (1889,  p.  138),  Australia. 

II.  Uterine  eggs  not  containing  hooked  embryos.     Opening  of  penis 
mediad  to  vaginal  opening. 

(1)  Opening  of  penis  posterior  to  vaginal  opening. 

(a)  Eggs  without  operculum. 

G.  urna. 

Host:  Chimaera  monstrosa.  Wagener  (1852,  p.  545).  Nice. 
Kroyer,  I)anmark's  Fiske,  v.  3,  p.  813.  Van  Beneden 
and  Hesse  (1864,  p.  54).  Olsson  (1868,  p.  58;  1896,  p. 
508).  Lonnberg  (1891,  p.  14).  Bergen,  Christiania. 
Monticelli  (1889b,  p.  229;  1889b,  p.  327).  Mediterranean. 
Hansson.  Free-living  off  the  west  coast  of  Sweden. 
(Lonnberg,  1891,  p.  14). 

(b)  Eggs  with  operculum. 

G.  nigrosetosa. 

Host:    Chimaera   ogilbyi,   Haswell    (1902,    p.    48).    Australia. 

(2)  Opening  of  penis  at  the  same  level  as  vaginal  opening. 
G.  urna  (var?) 

Host:  Chimaera  colliei,  from  the  California  coast.  Has 
been  found  attached  by  terminal  rosette  to  mucosa  of 
spiral  valve. 

B.  Frills  of  posterior  rosette  complex.     Opening  of  penis  mediad  to 
vaginal  opening,  at  same  level. 

G.  fimbriata. 

Host:  Chimaera  colliei:  off  the  California  coast.  Has  been 
found  attached  as  above,  free  in  intestine,  and  in  mouth 
and  on  gills  of  host. 


1911]  Watson:  The  Genus  Gyrocotyle.  383 

D.     GENERAL  MORPHOLOGY  AND  HISTOLOGY  OF 
GYROCOTYLE. 

I.  MATERIAL  AND  METHODS. 

The  structure  of  the  worm  has  been  studied  in  living  speci- 
mens, in  whole  mounts  stained  and  cleared,  and  in  serial  sections. 
The  following  killing  fluids  were  used:  Gilson's  fluid,  aceto- 
sublimate,  Zenker's  fluid  and  Vom  Rath's  mixture.  The  greatest 
difficulty  is  found  in  preventing  extreme  contraction  of  the  speci- 
mens. Stupefaction  with  chloretone  resulted  in  contraction  as 
intense  as  that  produced  by  the  killing  fluid :  the  use  of  hot 
reagents  was  of  some  small  advantage.  Flattening  between  plates 
of  glass  gave  the  least  contraction,  but  had  the  disadvantage  of 
producing  some  distortion.  The  best  results  were  obtained  from 
specimens  killed  in  Zenker's  fluid;  the  poorest  from  those  killed 
in  Gilson's  fluid.  It  is  difficult  to  obtain  good  infiltration  with 
paraffine,  especially  in  the  normal  (not  flattened)  specimens. 
The  modification  of  Apathy's  method  given  by  Lee  was  very 
successful,  leaving  the  tissues  in  good  condition.  High  tempera- 
tures (over  50°  C.)  are  rapidly  fatal  to  the  integrity  of  the  tis- 
sues. The  shortest  possible  time  in  paraffine  of  the  lowest  melting 
point  that  can  be  used  gives  the  most  satisfactory  result. 

The  worm  is  very  difficult  to  section  because  of  the  great 
mass  of  eggs  it  contains.  Various  macerating  agents  were  tried, 
but  none  was  of  any  great  service.  Sections  were  cut  as  thin  as 
4/x;  most  of  the  series  ranged  from  8/*  to  16/*,  the  latter  in  col- 
lodion. 

The  stains  used  were :  Heidenhain  's  iron  haematoxylin, 
Benda's  iron  haematoxylin,  Mayer's  acid  haemalum,  Mallory's 
connective  tissue  stain,  Delafield's  haematoxylin,  Ehrlich's 
haematoxylin,  Lonnberg's  borax  carmine-Lyons  blue,  toluidin 
blue.  Iron  haematoxylin  preparations  are  excellent  for  the  study 
of  cuticula,  musculature  and  sex-cells;  they  are  worthless  for 
the  study  of  the  nervous  system  and  unreliable  in  many  details. 
No  statements  are  based  on  results  given  by  this  stain  alone. 

Mallory's  connective  tissue  stain  colored  nervous  tissue,  with 
the  exception  of  the  nuclei,  bright  blue.  Its  action  was  too 


384          I' n i versify  of  California  Publications  in  Zoology.     [VOL.  6 

uneven  to  be  of  special  value.  Mayer's  acid  haemalum,  Dela- 
field's  haematoxylin  and  Ehrlich's  haematoxylin  gave  satisfac- 
tory results  for  general  morphology.  Lonnberg's  borax  carmine- 
Lyon's  blue  method  gave  the  best  result  for  the  study  of  the 
nervous  system.  This  in  general  is  the  method  used  by  Lonn- 
berg  in  his  work  on  Gyrocotyle.  A  brief  description  of  the 
process  is  given  by  him  (Lonnberg,  1891).  The  material  is 
stained  in  toto  in  Grenadier's  alcoholic  borax  carmine,  60% 
alcohol,  decolorized  in  acid  alcohol  (5  drops  cone.  HC1  to  lOO 
cc.)  ;  after  sectioning  and  mounting  the  sections  are  run  very 
quickly  through  absolute  and  90%  alcohol  to  a  saturated  solution 
of  Lyon's  blue  in  60%  alcohol,  plus  three  drops  n/10  HC1  to 
35  cc.  of  stain,  where  they  remain  fifteen  minutes.  The  sections 
are  decolorized  in  ammoniacal  85%  alcohol  made  up  of  one  part 
85%  just  basic  to  litmus  to  4  parts  neutral  85%.  Decolorization 
requires  from  two  to  three  minutes  and  must  be  stopped  when 
the  sections  appear  violet  in  color.  On  washing  in  neutral  90% 
the  differentiation  takes  place.  The  sections  must  not  be  left 
in  90%  or  absolute  longer  than  one  or  two  seconds,  else -the  stain 
is  blurred.  This  method  gives  beautiful  preparations  in  so  far 
as  differentiation  of  tissues  is  concerned,  but  is  rather  poor  for 
cytological  differentiation,  especially  in  cell-boundaries. 

The  nervous  system  stains  uniformly  a  light  blue,  easily  dis- 
tinguished from  all  other  tissues  except  condensed  connective 
tissue.  The  blue  is  clearer  in  the  nerves  than  in  the  connective 
tissue;  the  nervous  tissue  can  easily  be  recognized  with  a  fair 
degree  of  certainty  by  this  fact,  coupled  with  its  distinctive 
histological  structure. 

The  statement  generally  made  that  Lyon's  blue  should  be 
used  in  very  dilute  solution  for  corrosive  sublimate  material  is 
not  applicable  in  this  case.  Weak  solutions  give  no  result,  for 
all  the  color  drops  out  at  once,  leaving  no  differentiation. 

II.    BODY-COVERING    AND    SPINES. 

The  body  is  covered  by  a  thin  membrane,  composed  of  finely 
felted  fibres  imbedded  in  a  homogeneous  matrix  (cut.,  pi.  42,  figs. 
55,  58).  These  fibres  are  exceedingly  delicate,  tangled  in  an 
irregular  fashion,  but  in  general  parallel  to  the  surface  of  the 


1911]  Watson:  The  Genus  Gyrocotyle.  385 

body.  The  outer  surface  of  the  membrane  is  bounded  by  a  fine, 
deeply  stained  layer  of  ragged  fibres  (ext.  cut.  I.).  This  is  seen 
only  in  perfectly  preserved  specimens.  Vesicles  occur  frequently 
in  the  membrane.  There  are  also  breaks  in  the  margin,_resem- 
bling  sections  of  the  "pore-canals"  figured  by  Blochmann  (1896), 
The  thickness  of  this  membrane  varies  in  different  regions,  being 
slightly  less  on  the  lateral  folds  and  on  the  surface  of  the  aceta- 
bulum.  The  average  thickness  on  the  surface  of  the  body  proper 
is  about  3.8/x ;  on  the  lateral  folds,  etc.,  about  2/x,.  This  membrane 
will  be  referred  to  as  a  "  cuticula, ' '  following  the  common  usage 
among  writers  on  the  subject;  but  the  word  is  not  used  in  its 
strict  sense,  as  denoting  a  body-covering  derived  from  an  under- 
lying epidermis.  The  cuticula  of  Gyrocotyle  may  or  may  not  be 
derived  from  the  *  *  subcuticular ' '  layer  referred  to  below ;  struc- 
tural relations  indicate  that  it  is,  but  in  the  opinion  of  the  writer 
the  question  can  only  be  settled  by  embryological  data  which  are 
not  available. 

Lonnberg  (1891)  describes  a  two-layered  cuticula,  agreeing 
in  general  with  the  appearance  of  that  of  G.  fimbriata;  but  he 
describes  the  fibres  seen  in  the  "  Hauptschichte "  or  principal 
layer,  as  running  perpendicular  to  the  surface.  He  finds  this 
only  in  sections  in  which  the  cuticula  is  torn  or  affected  by 
reagents;  from  appearances  presented  in  similar  sections,  the 
writer  thinks  he  was  probably  dealing,  not  with  the  cuticular 
layer,  but  with  a  layer  of  perpendicular  fibres  lying  beneath  the 
cuticular  muscles,  to  be  described  later. 

Immediately  beneath  the  cuticula  (cut.  trans.,  pi.  42,  fig. 
55)  is  a  layer  of  cuticular  muscle-fibres  running  round  the  body 
at  right  angles  to  its  long  axis  (cut.  trans.,  pi.  42,  fig.  58).  Close 
beneath  this  layer  lies  a  set  of  longitudinally  arranged  muscle- 
fibres  (cut.  long.)  ;  these  are  heavier  than  the  transverse  fibres. 
These  layers  of  muscles  are  distinguished  as  the  cuticular  muscu- 
lature. Some  distance  below  these  muscle  fibres  is  an  irregular 
layer  of  large  nuclei,  about  twice  the  size  of  the  ordinary  paren- 
chyma nucleus,  resting  on  and  often  imbedded  in  the  outer 
transverse  layer  of  body  musculature  (sub.  cut.).  This  layer 
may  be  one  or  two  nuclei  deep,  or  it  may  be  from  five  to  eight 
deep.  In  the  neighborhood  of  a  spine  the  layer  becomes  three 


386          University  of  California  Publications  in  Zoology.     tv°L-  6 

to  five  times  its  ordinary  depth.  These  nuclei,  the  "Matrix- 
zellen"  of  Lonnberg,  are  richly  supplied  with  chromatin. 
Definite  cell-boundaries  can  sometimes  be  seen;  the  cytoplasm 
stains  deeply  and  shows  a  granular  structure.  The  writer  Avas 
unable  to  establish  any  processes  running  from  these  cells  out 
to  the  cuticula  through  the  cuticular  muscle-fibres,  or  to  make 
out  any  structural  connection  existing  between  cuticula  and 
subcuticula.  The  space  between  the  subcuticular  layer  and  the 
longitudinal  cuticular  muscles  is  filled  with  very  delicate  muscle- 
fibres  (sag.  fib.)  and  thread-like  processes  of  the  subcuticular  cells, 
taking  in  general  a  direction  perpendicular  to  the  surface.  There 
are  also  many  fibres  running  parallel  to  the  surface,  as  shown  in 
transverse  section  by  their  cut  ends,  but  these  are  not  so  conspicu- 
ous as  the  perpendicular  threads.  It  was  probably  this  layer 
which  Lonnberg  mistook  for  the  principal  layer  of  the  cuticula 
in  his  sections.  The  writer  has  found  similar  appearances,  due 
to  the  fact  that  the  cuticula  is  very  easily  affected  by  reagents. 
In  a  specimen  preserved  in  early  stages  of  decomposition  or 
imperfectly  fixed  by  the  killing  fluid,  the  cuticula  is  almost 
invariably  found  to  be  sloughing  off  in  thin  strips,  broken, 
notched  and  ragged.  It  presents  both  horizontal  and  perpendi- 
cular planes  of  cleavage,  but  shows  a  marked  tendency  to  split 
in  layers  parallel  to  the  body-surface.  This  is  the  only  indica- 
tion of  lamination  noticed;  it  is  more  justly  interpreted  as  a 
splitting  in  the  direction  taken  by  the  greater  portion  of  the 
fibres  of  which  it  is  composed. 

The  cuticula  in  the  region  of  the  rosette  shows  marked 
changes.  That  lining  the  funnel  is  noticeably  thinner,  the 
cuticular  muscular  layers  are  much  reduced,  and  the  subcuticular 
cells  are  very  few.  As  the  much-folded  margin  of  the  funnel  is 
approached,  the  subcuticular  cells  of  the  outer  wall  also  become 
much  reduced,  sink  deeper  and  cease  to  be  a  distinct  layer;  lying 
within  them  large  gland  cells  can  be  seen.  In  the  writer's 
opinion  these  are  not  related  to  the  subcuticular  cells  but  belong 
to  the  central  part  of  the  body  just  as  do  the  shell-glands  and 
the  prostate  glands,  arising  in  the  neighborhood  of  the  inner 
longitudinal  muscular  layer. 

The  most  prominent  feature  of  the    body-covering    is    the 


1911]  Watson:   The  Genus  Gyrocotyle.  387 

spines,  frequently  referred  to  in  the  preceeding  discussion  of 
the  literature  of  the  subject.  In  G.  fimbriata,  the  spines  are 
arranged  in  a  definite  pattern,  from  which  there  is  no  great 
amount  of  individual  variation,  though  the  number  of  spines 
varies  considerably.  At  the  anterior  extremity,  on  the  lateral  fin 
on  each  side  of  the  acetabulum  are  two  groups  of  large  spines 
(pi.  36,  figs.  22,  23).  They  are  arranged  in  five  rows,  two  each 
on  the  dorsal  and  ventral  surfaces  and  one  row  on  the  margin. 
There  are  from  five  to  seven  spines  in  a  row,  from  20  to  30  in 
each  group.  Here,  as  elsewhere,  the  spines  are  borne  on  rounded 
papillae,  which  are  in  this  region  of  greater  size  than  elsewhere 
on  the  body,  except  around  the  "neck"  of  the  rosette.  The 
papillae  extend  back  along  the  lateral  fin  to  the  beginning  of 
the  lateral  folds,  but  bear  spines  only  at  the  region  shown  in 
the  figure,  at  the  level  of  the  posterior  half  of  the  acetabulum. 
In  addition  to  these  large  spines,  of  the  shape  shown  in  fig.  28, 
there  are  a  number  of  very  much  smaller,  less  definitely  shaped 
spines  (pi.  37,  fig.  32),  in  among  the  larger  ones. 

There  are  no  spines  on  either  surface,  throughout  the  length 
of  the  body,  back  to  the  posterior  border  of  the  receptaculum 
seminis.  Here  on  the  ventral  surface  two  groups  of  spines  appear, 
near  the  base  of  the  lateral  folds,  extending  backward  in  con- 
verging lines  toward  the  canal  opening.  They  flank  this  opening, 
increasing  in  number  and  size,  and  spread  out  posteriorly  on  the 
surface  of  the  neck  of  the  rosette  in  its  median  half.  At  the 
posterior  border  of  the  neck  they  extend  laterally,  passing  around 
to  the  dorsal  surface.  On  the  extreme  lateral  margins  of  the 
ventral  surface  appear  two  groups  of  spines,  which  pass  over  on 
the  dorsal  surface,  forming  with  the  ring  above  described  a  belt 
of  spines  on  the  dorsal  surface  of  the  neck.  The  number  and 
direction  of  these  spines  is  shown  in  the  figures  (pi.  34,  figs. 
10,  12). 

In  G.  urna  (var.  ?)  the  distribution  of  spines  (pi.  36,  fig.  24; 
pi.  34,  figs.  11,  13)  is  markedly  different.  The  ventral  surface, 
to  the  level  of  the  uterus  opening,  is  thickly  set  with  large 
spines ;  there  is  no  special  pattern  in  the  arrangement  about  the 
neck,  there  being  six  or  seven  irregular  rows  of  spines,  encircling 
the  base  of  the  rosette.  On  the  dorsal  surface  the  spines  are 


388          University  of  California  Publications  in  Zoology.     [VOL-  6 

fewer  and  scattered  irregularly  over  the  whole  surface.  It 
should  be  noted  that  the  two  marginal  clumps  of  spines  at  the 
level  of  the  acetabulum  occur  as  they  do  in  G.  fimbriata. 

The  distribution  of  spines  was  worked  out  in  living  as  well 
as  preserved  material,  that  no  error  due  to  loss  of  spines  by 
deterioration  or  action  of  reagents  might  enter.  The  distribu- 
tion found  resembles  that  given  by  Lonnberg  for  G.  urna,  except 
that  he  describes  spines  as  present  along  the  whole  length  of  the 
lateral  margins  of  the  body,  and  along  the  lateral  folds.  The 
distribution  as  given  by  Spencer  (1889,  p.  140)  for  G.  rugosa  is 
substantially  that  found  in  G.  urna  (var.?)  : 

"They  are  distributed  generally  over  the  body  surface,  but  are  most 
numerous  along  the  side  folds,  and  more  especially  at  the  anterior  endr 
both  on  the  dorsal  and  ventral  surfaces,  and  again  at  the  posterior  end, 
beyond  the  region  of  the  side  folds.  They  are  sparsely  distributed  over 
the  central  part  of  the  body,  both  dorsally  and  ventrally. ' ' 

Haswell's  figures  (see  my  plate  47,  figure  80)  show  spines  of 
great  size  distributed  over  the  whole  of  the  surface  of  the  animal. 
Wagener's  (1852)  figures  show  the  acetabular  clumps,  and  a 
distribution  of  the  spines  in  the  posterior  region  similar  to  that 
described  by  Lonnberg  and  given  above  for  G.  fimbriata. 

The  small  spines,  irregularly  distributed,  vary  in  size  from  40/*, 
to  60/n  by  15/x  to  25/x,  and  in  shape  from  simple  rounded  spinules 
to  a  blunt-tipped,  swollen-based  form.  Broad,  triangular, 
sharply  pointed  forms  also  occur,  but  less  frequently  (pi.  37r 
fig.  32).  These  spinules  are  not  borne  on  papillae;  they  rarely 
contain  more  than  three  concentric  layers. 

The  spines  proper,  from  the  extremities  of  the  body,  are  of 
fairly  constant  shape  and  size.  In  the  acetabular  region  (pi.  37, 
figs.  28,  29)  they  are  bluntly  rounded  at  the  tip,  swollen  in  the 
middle  third  of  their  length  to  nearly  three  times  the  diameter 
of  the  tip,  narrowing  again  at  the  bluntly  rounded  base.  They 
are  about  130/x  by  36/x  in  size.  In  the  rosette  region,  the  spines 
are  of  the  same  general  shape  (pi.  37,  figs.  30,  35),  but  are  of 
considerably  greater  size,  ranging  from  185/t  by  45/x  to  220/w. 
by  55/ut. 

The  spines  are  composed  of  concentric  layers  of  uniform 
thickness,  and  are  hollow.  In  macerated  specimens  the  layers. 


1911]  Watson:   The  Genus  Gyrocotyle.  389 

are  seen  to  be  composed  of  a  finely  felted  mass  of  fibres,  circular 
in  general  direction,  embedded  in  a  homogeneous  interstitial  sub- 
stance which  is  acted  on  by  the  macerating  agent  (which  also 
removes  the  cuticula  from  the  body)  (pi.  37,  fig.  33).  Each  spine 
is  set  in  a  pit  lined  with  a  very  thin  cuticula  of  felted  fibres  (par. 
felt,  pi.  37,  fig.  34)  which  passes  indistinguishibly  into  the  fibres 
of  the  surrounding  parenchyma.  The  spine  is  surrounded  by 
muscle-bundles,  which  serve  to  protrude  and  retract  the  spine. 
The  retractors  are  muscle-bundles  from  the  outer  transverse 
layer  of  the  body  musculature;  they  insert  at  the  base  of  the 
spine  (pi.  37,  fig.  30).  The  protractors  are  bundles  of  fibres 
inserted  at  the  base  and  for  some  distance  on  the  sides  of  the 
spine ;  they  originate  or  are  attached  to  the  cuticular  musculature, 
principally  to  its  transverse  layer. 

The  direction  of  the  spines  is  shown  in  the  figures  (pi.  34, 
figs.  10-13).  In  general  they  may  be  said  to  be  directed  anter- 
iorly and  laterally.  This  is  the  most  advantageous  arrangement 
possible  for  maintaining  the  attachment  of  the  parasite  to  its 
host ;  the  position  of  the  greatest  number  of  spines  on  the  ventral 
surface  and  around  the  rosette  also  further  this  end.  For  loco- 
motion, the  spines  seem  to  be  arranged  to  hinder  rather  than 
help;  but  they  are  probably  so  completely  retracted  that  their 
rounded  ends  offer  no  special  resistance  to  the  forward  move- 
ments of  the  worm.  At  all  events,  however  theoretically  difficult 
their  arrangement  and  direction  render  locomotion,  the  worm 
does  move,  and  with  considerable  rapidity,  in  spite  of  them. 
Naturally,  ease  of  locomotion  is  a  secondary  and  firmness  of 
attachment  a  primary  consideration  in  the  economy  of  this 

creature. 

III.  MUSCULATURE. 

The  musculature  of  Gyrocotyle  is  exceedingly  well  developed, 
and  composed  of  powerful,  neatly  balanced  sets  of  muscles.  It 
constitutes  the  great  bulk  of  the  body.  This  is  not  surprising, 
when  the  extreme  contractility  and  general  activity  of  the  worm 
is  considered. 

In  general,  muscles  are  grouped  in  pairs  running  at  right 
angles  to  each  other.  There  is  throughout  the  body,  but  espe- 
cially prominent  in  the  region  between  the  acetabulum  and  the 


390          University  of  California  Publications  in  Zoology.     [y°L-  6 

canal  opening,  a  set  of  sagittal  fibres,  very  delicate,  not  organized 
into  bundles,  running  from  the  outer  cuticular  muscle  layer  of 
the  dorsal  surface  to  that  of  the  ventral  surface.  The  fibres 
insert  directly  in  the  cuticula,  as  do  those  of  the  protractors  of 
the  spines. 

In  addition  to  these  sagittal  fibres,  six  distinct  coats  of  muscle 
fibres  can  be  distinguished,  in  the  body  proper.  These  may  be 
grouped  according  to  their  action,  which  gives  us  three  sets  of 
opposing  muscles,  each  set  a  longitudinal  opposed  to  a  transverse ; 
or  they  may  be  grouped  according  to- their  position  with  respect 
to  the  other  tissues  of  the  body.  Such  a  division  gives  us  two 
groups,  one  of  which  may  be  again  subdivided  into  two. 

1.  Peripheral,  including  all  muscles  lying  without  the  vitel- 
laria.    May  be  divided  into : 

(a)   Cuticular,  including  all  muscles  lying  without  the  sub- 

cuticula  or  "Matrix-zellen." 
(6)   Intermediate,  including  all  muscles  lying  between  the 

subcuticula  and  the  vitellaria. 

2.  Central,  muscles  lying  within  the  vitellaria. 

The  cuticular  muscles  have  been  described  in  connection  with 
the  cuticula  (p.  385).  Immediately  beneath  the  subcuticular  cells, 
frequently  invading  their  territory,  is  a  layer  of  muscle-bundles 
directed  around  the  body,  at  an  angle  of  about  60°  to  its  main 
axis.  Thus  in  a  cross-section  we  get  only  broken  segments  of  this 
layer,  not  a  continuous  sheet,  as  in  the  deeper-lying  transverse 
muscle  layer.  These  fibres  run  in  two  interlacing  sets  whose 
directions  are  at  an  angle  of  60°  to  each  other.  These  bundles  all 
break  through  the  subcuticula  to  insert  by  fine  threads  on  the 
cuticula  (pi.  42,  fig.  55). 

Immediately  beneath  the  outer  transverse  layer  above 
described  are  found  the  bundles  of  fibres  running  parallel  to  the 
longitudinal  axis  of  the  body.  These  are  heavier  and  grouped 
into  more  definite  bundles  than  any  previously  described.  The 
layer  is  one  or  two  bundles  thick  and  occurs  over  the  whole  body, 
but  becomes  very  thin  in  the  region  of  the  lateral  folds.  These 
fibres  insert  on  the  cuticular  musculature,  and  with  the  outer 
transverse  just  described  produce  the  transverse  ridges  so  char- 
acteristic of  the  worm  in  its  contracted  state.  Within  this  laver 


1911]  Watson:  The  Genus  Gyrocotyle.  391 

lie  the  inner  transverse  muscles,  a  very  heavy  sheet  of  fibres 
running  at  right  angles  to  the  longitudinal  axis,  around  the  body. 
These  fibres  also  are  continued  for  some  distance  into  the  region 
of  the  lateral  folds,  but  are  considerably  reduced.  These  muscle 
layers  constitute  the  peripheral  musculature  and  arF  found 
throughout  the  whole  body,  though  less  and  less  strongly  devel- 
oped the  further  laterad  they  pass. 

Within  the  inner  transverse  muscles  lie  the  vitellaria,  the 
large  excretory  canals,  the  central  nervous  system,  the  glands 
of  the  reproductive  system,  and  the  strongest  muscles  of  the 
body,  the  inner  longitudinal.  In  the  region  of  the  body  anterior 
to  the  testes  and  posterior  to  the  ovaries,  these  muscle-bundles 
occupy  the  whole  of  the  space  inside  the  vitellaria.  In  the  inter- 
mediate region,  especially  in  the  region  of  the  uterus,  the  layer  is 
considerably  reduced,  and  pushed  to  one  side.  It  is  quite  thick 
ventrally,  but  there  are  very  few  fibres  dorsal  to  the  uterus. 
These  longitudinal  fibres  insert  on  the  acetabulum,  and  around 
the  neck  of  the  rosette  and  on  the  walls  of  the  canal.  It  is  by 
the  contraction  of  these  powerful  muscles  that  the  worm  moves 
about,  thrusts  forth  and  around  and  withdraws  the  proboscis- 
like  acetabulum,  and  firmly  attaches  the  posterior  rosette. 
Furthermore,  as  Lonnberg  pointed  out,  this  muscle  layer  being 
absent  in  the  lateral  frills,  and  the  outer  longitudinal  fibres  being 
very  weakly  developed  there,  on  contraction  of  the  longitudinal 
muscles  the  lateral  folds  are  increased  in  amplitude.  Lonnberg 
regards  the  frills  as  due  wholly  to  contraction  of  the  body  mus- 
culature ;  the  writer,  in  agreement  with  Wagener,  regards  them  as 
independent  structures,  existing  in  all  states  of  expansion  of  the 
animal. 

The  musculature  of  the  acetabular  region  (pi.  40,  fig.  43) 
shows  plainly  the  origin  of  the  acetabulum  as  an  invagination  of 
the  anterior  extremity  of  the  body.  There  is  a  doubling  of  the 
layers,  giving  twelve  instead  of  six.  By  inverting  the  anterior 
extremity  we  get  a  mass  of  predominantly  longitudinal  muscles, 
corresponding  to  the  inner  longitudinal  body-layer,  on  the  out- 
side of  the  acetabulum.  These  fibres  are  meridional  with  refer- 
ence to  the  acetabulum  as  a  whole  and  constitute  more  than  half 
its  bulk.  Inserting  along  the  surface  of  this  mass  are  the  inner 


392          University  of  California  Publications  in  Zoology.     [VOL-  6 

longitudinal  muscles  of  the  body,  most  numerous  toward  the 
anterior  extremity  and  in  large  masses  around  the  margin  of 
invagination ;  on  contraction  of  the  inner  longitudinal  muscles, 
the  whole  mass  of  the  acetabulum  is  drawn  back  (pi.  40,  fig.  43). 
This  is  the  state  invariably  found  in  killed  specimens.  In  the 
living  animal  in  the  expanded  state  the  mouth  of  the  acetabulum 
is  at  the  anterior  extremity  (pi.  33,  figs.  7,  9)  ;  further  evagina- 
tion  is  impossible.  The  great  lengthening  of  this  region  observed 
in  active  specimens  must  be  due  to  expansion  of  the  acetabulum 
itself. 

The  fibres  of  the  outermost  layer  (out.  mer.),  constituting 
the  bulk  of  the  acetabulum,  are  derived  from  the  inner  longi- 
tudinal layer  of  the  body  and  are  meridional  in  direction,  pre- 
senting in  section  a  margin  of  cut  edges  surrounding  the  aceta- 
bulum. This  layer  is  densely  supplied  with  finer  radial  fibres 
(rad.  fib.),  at  right  angles  to  the  long  axis  of  the  acetabulum, 
passing  from  dorsal  to  ventral  surface.  These  are  the  homo- 
logues  of  the  sagittal  fibres  of  the  body  musculature,  greatly 
increased  in  size. 

Immediately  within  this  outer  heavy  layer  lies  a  set  of  fibres 
predominantly  transverse  (out.  arc.),  passing  from  left  to  right 
of  the  acetabulum,  the  homologue  of  the  inner  transverse  layer 
of  the  body.  This  layer  is  even  more  abundantly  supplied  with 
radial  fibres  than  is  the  outermost  one.  These  pass  from  dorsal 
to  ventral,  at  right  angles  to  the  radial  fibres  of  the  outer  layer. 
Within  this  layer  is  a  second  set  of  meridional  fibres  (in.  mer.)  • 
the  homologues  of  the  outer  longitudinal  muscles  of  the  body, 
followed  by  a  thin  layer  of  fibres  passing  circularly  around  the 
opening  of  the  acetabulum,  corresponding  to  the  outer  transverse 
muscles  of  the  body.  Lying  next  to  the  cuticula  are  thin  longi- 
tudinal and  transverse  layers,  the  homologues  of  the  cuticula r 
musculature  elsewhere.  At  the  mouth  of  the  acetabulum  a 
special  sphincter  muscle  has  been  developed,  composed  of  fibres 
from  the  inner  transverse,  the  inner  longitudinal  and  the  circular 
muscle  layers  of  the  acetabulum  (acet.  sphinc.).  Most  of  the 
fibres  are  circular  in  direction ;  they  are  grouped  in  heavy  bundles 
and  form  a  large  ring-muscle  about  the  acetabular  opening. 

The  musculature  of  the  funnel-region  has  been  worked  out 


Watson:  The  Genus  Gyrocotyle.  393 

by  Lonnberg  (1891).  There  is  here  a  doubling  of  layers,  due  to 
folding  on  the  ventral  surface,  and  an  increase  in  the  inner  trans- 
verse layer  to  produce  two  "wing-muscles."  Lonnberg 's  tabula- 
tion of  the  funnel  muscles  and  their  homologues  in  Gyrocotyle 
urna  the  writer  finds  substantially  correct  for  G.  fimbridJarHere 
as  in  the  acetabulum  the  development  has  been  mainly  in  the 
inner  transverse  layer,  and  in  the  sagittal  fibres.  By  means  of 
these  a  very  effective  sphincter  is  produced  at  the  base  of  the 
rosette.  Posterior  to  the  collar  or  "neck"  (the  region  occupied 
by  this  sphincter)  and  anterior  to  it  near  the  canal  opening,  the 
development  of  the  transverse  muscle  layer  is  much  reduced, 
though  still  greater  than  in  the  body  in  general. 

Lonnberg  concludes  from  the  above  described  arrangement  of 
muscle  layers  that  the  rosette  and  canal  were  formed  by  a  fold- 
ing from  the  posterior  extremity  forward  in  the  ventral  surface. 
This  was  first  a  furrow  or  trough,  which  functioned  as  a  sucker,  a 
condition  common  among  the  lower  cestodes;  later  the  ventral 
walls  fused  to  form  a  tube,  and  finally  only  the  most  posterior 
part  of  the  tube  functioned  as  an  organ  of  attachment,  its 
anterior  extremity  remaining  open  as  the  present  ventral  open- 
ing of  the  canal.  Lonnberg  hazards  no  opinion  as  to  the  signifi- 
cance of  this  anterior  canal  opening.  Observations  on  the 
attached  worm  show  that  the  mouth  of  the  opening  is  always 
closed  wrhile  the  rosette  is  attached  to  the  mucosa.  When  the 
canal  mouth  opens,  flaring  out  as  in  Spencer's  figure  2,  the  hold 
of  the  rosette  loosens  and  the  worm  drops  from  the  mucosa. 
During  attachment  there  is  a  series  of  waves  of  contraction,  run- 
ning from  the  margin  of  the  rosette  forward  to  the  canal  open- 
ing. The  whole  posterior  extremity  thus  forms  a  suction-cup  of 
high  efficiency.  The  musculature  of  the  ventral  canal-opening, 
developed  from  the  peripheral  muscles,  is  shown  in  plate  40, 
figure  44. 

The  finer  structure  of  the  muscles  in  Gyrocotyle  is  very 
simple.  The  sagittal  fibres  (radial  fibres  of  acetabulum  and 
rosette  collar)  are  not  aggregated  into  bundles  but  are  simple 
strands  running  through  the  body,  distinguished  from  parenchy- 
ma! fibres  by  their  size  and  also  by  the  position  of  the  nucleus 
(pi.  42,  fig.  57).  This  lies  to  one  side  of  the  fibre,  forming  a 


394          University  of  California  Publications  in  Zoology.     [VOL.  6 

bulging  prominence.  These  nuclei  are  larger  and  more  easily 
seen  than  those  of  the  other  muscle  fibres;  this  is  in  harmony 
with  the  generally  primitive  and  undifferentiated  character  of 
this  set  of  muscle  fibres.  In  the  outer  transverse  muscle  layer 
the  fibres  are  longer,  very  slightly  swollen  in  the  middle  of  their 
length,  where  the  nucleus  lies  very  closely  applied  to  one  side 
of  the  fibre.  The  nucleus  also  is  elongated,  rather  than  round  as 
in  the  dorso- ventral  fibre  (pi.  42,  fig.  57).  In  the  two  inner 
layers,  the  inner  circular  and  the  inner  longitudinal,  the  nucleus 
is  very  hard  to  distinguish  (pi.  42,  fig.  56).  The  fibres  are  heavy, 
elongated,  tapering  gradually  toward  their  extremities.  The 
nucleus  is  exceedingly  slender,  flattened  against  the  surface  at 
one  side  of  the  fibre,  but  still  within  the  fibre.  In  cross-sections 
of  fibres  the  nucleus  is  difficult  to  distinguish,  appearing  merely 
as  a  thickening  of  the  cell- wall;  in  longitudinal  sections  it  can 
be  made  out  more  easily.  Had  not  the  nucleus  appeared  so  un- 
mistakably in  the  outer  and  sagittal  muscles,  it  probably  would 
have  been  overlooked  in  these  inner  fibres. 

In  the  cuticular  muscle  fibres  there  is  no  trace  of  a  nucleus. 
The  fibres  are  slender,  long,  of  even  diameter.  Those  of  the 
transverse  layer  are  exceedingly  fine,  while  the  longitudinal  ones 
are  of  ordinary  diameter.  The  great  number  of  processes  run- 
ning from  the  subcuticular  cells,  apparently  to  insert  in  the  cuti- 
cular musculature,  suggests  most  strongly  that  some  of  these 
cells,  at  least,  are  the  myoblasts  of  the  cuticular  musculature. 
The  fact  that  elsewhere  in  the  body  the  nucleus  lies  in  the  fibre 
makes  this  seem  improbable,  yet  the  writer  is  at  a  loss  to  explain 
the  processes  and  their  connection  with  the  musculature  in  any 
other  way. 

All  the  fibre  bundles  are  penetrated  throughout  and  en- 
wrapped by  parenchymal  threads,  with  their  accompanying 
nuclei.  The  latter  can  always  be  distinguished  from  muscle- 
nuclei  by  their  shape  and  size,  as  well  as  by  position. 

It  is  of  interest  to  note  that  Salensky  (1874)  found  in  Amphi- 
lina  foliacea  smooth  muscle  fibres  with  laterally  attached  myo- 
blast,  this  being  one  of  the  earliest  cases  in  which  a  nucleus  for 
a  muscle  fibre  was  discovered.  Furthermore,  the  description 
above  given  of  laterally  attached  nucleus  in  the  dorso- ventral, 


1911]  Watson:  The  Genus  Gyrocotyle.  395 

transverse  and  longitudinal  muscles  and  of  nucleus  some  distance 
removed  from  the  fibre  in  the  subcuticular  muscles,  corresponds 
to  the  classification  given  by  Braun  (1901,  p.  1351).  The  only 
difference  is  that  the  laterally  attached  nucleus  in  Gyrocotyle  is 
inside  the  fibre,  not  in  an  adjacent  myoblast.  The  occurrence  of 
nuclei  within  muscle  fibres  is  reported,  according  to  Braun  (1894, 
p.  1351)  in  the  scolex  of  the  Tetrarhyncha,  and  in  the  longitudinal 
muscles  of  the  proglottides  of  Taenia  dendritica.  That  a  form 
as  primitive  as  Gyrocotyle  should  exhibit  a  muscle  fibre  relatively 
simple  and  undifferentiated  as  compared  with  that  of  the  mero- 
zoic  cestodes,  is  exactly  what  other  facts  in  its  structure  would 
lead  one  to  expect. 

The  staining  reactions  of  the  muscle-fibres  are  of  some 
interest.  With  iron  hematoxylin  and  toluidin  blue  the  whole 
fibre  stains  very  intensely.  Preparations  by  these  methods  are 
excellent  morphologically,  mapping  out  the  muscles  most  sharply ; 
but  are  quite  worthless  histologically.  With  Mallory  's  connective 
tissue  stain,  muscle  fibres  stain  a  bright  red.  As  nuclei  also  stain 
red,  this  method  is  not  useful  for  a  study  of  muscle-nuclei.  The 
same  holds  true  for  borax  carmine-Lyon 's  blue  preparations. 
The  best  results  are  given  by  Delafield's  hematoxylin,  hematoxy- 
lin-eosin,  or  Mayer's  acid  haemalum,  and  counter-stains.  With 
these  the  muscle-fibre  stains  a  dull  blue-gray,  while  the  nucleus 
comes  out  sharply  in  blue-black. 

IV.  REPRODUCTIVE  ORGANS. 

The  organs  of  Gyrocotyle  include  the  following : 

1.  Female.     Ovaries,  receptaculum  ovorum,  vitellaria,  shell- 
glands,  uterus,  vagina,  and  receptaculum  seminis. 

2.  Male.      Testes,    vasa    efferentia,    vesicula    seminalis,    vas 
deferens,  penis,  and  prostate  glands. 

All  of  these  organs,  with  the  exception  of  the  vitellaria,  lie 
within  the  inner  longitudinal  muscles.  The  female  organs  are  in 
the  second  and  third  quarters  of  the  length  of  the  body ;  the  male 
organs  in  the  first  quarter. 

The  ovaries  (ovar.,  pi.  39,  fig.  42)  lie  laterad  of  the  uterus, 
at  its  posterior  border.  They  are  roughly  triangular  in  shape, 
the  lateral  lobes  united  in  the  median  line  just  posterior  to  the 


396          University  of  California  Publications  in  Zoology.     [VOL.  6 

receptaculum  seminis  by  a  small  median  portion.  They  are  com- 
posed of  numerous  rounded  follicles,  from  which  run  collecting 
tubules  to  empty  into  five  main  oviducts,  one  posterior,  two 
lateral  and  two  anterior  ducts.  These  lead  into  the  receptaculum 
ovorum,  which  is  embedded  in  a  mass  of  loose  tissue  in  a  depres- 
sion on  the  anterior  dorsal  surface  of  the  receptaculum  seminis. 
The  receptaculum  ovorum  (rec.  ov.,  pi.  45,  figs.  73,  75),  is 
about  3  mm.  in  its  antero-posterior  and  its  dorso-ventral  diam- 
eter and  about  6  mm.  in  transdiameter.  These  measurements  are 
the  average  for  several  sexually  mature  worms. 

The  vitellaria  are  composed  of  loosely-grouped  follicles,  each 
containing  ten  or  fifteen  cells,  lying  just  within  the  inner  trans- 
verse musculature  and  outside  the  inner  longitudinal.  The  fol- 
licles are  present  throughout  the  body  with  the  following  excep- 
tions :  (1)  dorsal  and  ventral  to  the  uterus,  that  is,  in  the  median 
third  of  the  body  in  the  two  middle  quarters  or  more  of  its 
length;  (2)  anterior  to  the  posterior  border  of  the  acetabulum; 
(3)  posterior  to  the  level  of  the  ventral  canal  opening. 

The  lateral  folds  are  densely  supplied  with  vitellarian  fol- 
licles, these  forming  the  greater  part  of  the  folds.  The  ducts 
of  these  yolk  glands  unite  into  four  main  lateral  ducts,  which 
empty  into  a  yolk  reservoir,  or  "Endstiick, "  which  lies  in  the 
dorsal  depression  of  the  receptaculum  seminis  above  mentioned, 
just  posterior  to  the  receptaculum  ovorum.  It  gives  off  a  single 
efferent  vitellary  duct,  which  enters  the  afferent  oviduct,  as 
described  below,  a  short  distance  back  of  the  entrance  of  the  duct 
connecting  the  efferent  oviduct  with  the  receptaculum  seminis. 

The  efferent  yolk-ducts  (pi.  39,  fig.  42,  vit.  d.),  appear  in 
stained  and  cleared  preparations  as  a  dark  brown  anastomosing 
network  of  delicate  threads,  spread  over  the  receptaculum 
seminis  and  the  first  three  or  four  coils  of  the  uterus,  and  con- 
verging to  the  yolk-reservoir  in  the  concavity  of  the  recep- 
taculum. 

From  the  ventral  surface  of  the  receptaculum  ovorum  is 
given  off  in  the  median  line  a  single  efferent  duct  (ef.  ovd.) 
which  receives  first  a  short  thick-walled  duct  from  the  recep- 
taculum seminis  (duct,  sem.)  ;  and  then  an  efferent  duct  from 
the  yolk  reservoir  (ef.  vit.d.,  pi.  45,  figs.  71-74).  This  duct 


1911]  Watson:  The  Genus  Gyrocotyle.  397 

(oot.)  then  becomes  the  uterus,  passing  to  the  left  of  the  recep- 
taculum  seminis  and  around  it  to  the  ventral  surface,  across  the 
ventral  surface  and  forward,  at  once  increasing  in  size.  The  first 
two  or  three  coils  of  the  uterus,  as  above  described,_may  be 
regarded  as  an  ootype.  They  are  surrounded  by  shell-glands,  and 
within  them  the  compound  eggs  are  formed.  In  the  dorsal 
(proximal)  part  of  the  first  coil,  and  to  the  left  of  the  receptac- 
ulum  seminis,  the  yolk-cells  are  seen  to  be  aggregating  about 
a  single  ovum  and  the  uterus  is  full  of  droplets  of  a  yellow  homo- 
geneous material,  which  form  a  coating  around  the  combined 
ovum  and  yolk-cells.  The  uterus  contains  fully  formed  eggs  in 
the  convolutions  anterior  to  the  receptaculum  seminis.  It  winds 
back  and  forth  across  the  median  third  of  the  body  through 
from  fifteen  to  twenty  convolutions,  the  duct  increasing  steadily 
in  size,  ending  finally  in  a  greatly  dilated  pouch  which  opens 
to  the  exterior  by  a  large  aperture  on  the  dorsal  surface  in  the 
median  line  posterior  to  the  opening  of  penis  and  vagina. 

The  uterus  is  lined  at  its  inception  and  throughout  its  course 
by  a  thin  fibrillated  layer,  increasing  in  thickness  from  the  pos- 
terior coils  forward.  This  layer  is  covered  with  fine  cilia,  in 
the  first  five  or  six  coils  of  the  uterus.  These  cilia  are  connected 
with  scattered  nuclei  beneath  the  cuticula,  by  means  of  delicate 
fibrils  strongly  suggesting  those  figured  by  Lonnberg  (1891) 
for  the  cilia  lining  the  excretory  canals.  Their  direction  is  in 
general  at  right  angles  to  the  course  of  the  uterus.  These  fibres 
lie  in  a  nucleated  meshwork  of  parenchymal  fibres,  which  pass 
indistinguishably  into  the  cuticular  lining  of  the  duct.  Further 
forward,  the  nucleated  circular  muscle  fibres  disappear,  and  a 
typical  subcuticular  layer  of  cells  appears  coincidently  with  the 
appearance  of  a  typical  cuticular  musculature,  suggesting  very 
strongly  a  structural  connection  between  subcuticular  and  cuti- 
cular musculature. 

The  shell-glands  (sh.  gl.,  pi.  39,  fig.  42)  are  an  aggregation  of 
large  cells,  with  characteristic  nuclei,  lying  close  to  the  recepta- 
culum seminis  on  its  dorsal,  ventral,  and  posterior  surfaces. 
This  relation  to  the  receptaculum  seminis  is  of  course  due  to  the 
fact  that  the  earliest  convolutions  of  the  uterus  lie  on  these  sur- 
faces of  the  receptaculum.  The  greatest  mass  of  cells  lies  to  the 


398          University  of  California  Publications  in  Zoology.     [VOL.  6 

right  and  left;  the  posterior  median  mass  is  very  thin.  The 
lateral  masses  extend  dorsally  and  ventrally  well  into  the  main 
longitudinal  muscle  mass,  and  in  general  the  dorsal  mass  is 
greater  than  the  ventral.  The  efferent  oviducts'  and  yolk-ducts 
pass  through  this  mass  of  gland  cells,  but  no  shell-material  is 
seen  except  in  the  first  coils  of  the  uterus.  The  cells  of  the  gland 
are  large,  swollen  at  the  base,  with  slender  "necks,"  leading  into 
intracellular  ducts  (pi.  44,  fig.  68).  These  ducts  appear  to  open 
independently  in  the  anterior  wall.  The  cytoplasm  of  the  gland 
cells  is  dense,  granular,  and  stains  very  intensely.  The  cell  wall 
is  sharply  defined.  The  nucleus  is  large,  cloudy,  with  deeply 
staining  border  and  faint  nucleolus.  The  nucleus  lies  in  the 
dilated  base  of  the  cell.  The  ducts  have  a  sharply  defined  lumen, 
and  are  of  considerable  size. 

The  receptaculum  seminis,  originally  described  by  Wagener 
(1852)  as  the  testis,  is  a  large  chamber,  convex  posteriorly, 
slightly  concave  dorso-anteriorly,  filled  with  a  dense  mass  of 
semen  (rec.  sem.,  pi.  39,  fig.  42).  It  might  be  regarded  as  the 
dilated  blind  end  of  the  vagina,  which  enters  its  dorsal  surface 
near  the  anterior  border.  The  receptaculum  seminis  measures 
about  1.5  mm.  by  1  mm.  by  1  mm.  It  is  surrounded,  as  above 
noted,  by  the  first  coils  of  the  uterus  and  their  accompanying 
shell-glands;  on  its  dorsal  surface  lie  the  yolk  reservoirs,  the 
receptaculum  ovorum,  and  their  efferent  and  afferent  ducts. 
From  the  dorsal  surface  of  the  receptaculum  is  given  off  a  short, 
thick-walled  duct,  the  ductus  seminalis,  to  the  efferent  oviduct. 

The  wall  of  the  receptaculum  seminis  (pi.  42,  fig.  59)  is  com- 
posed of  a  mass  of  finely  felted  fibres,  elongated  cells  with  large 
nuclei  and  granular,  non-fibrillated  cytoplasm.  Outside  this 
layer  are  found  scattered  cells  of  the  shell-glands.  This  differs 
markedly  from  Lonnberg's  description  (1891,  p.  41)  of  the  his- 
tology of  the  wall  of  the  receptaculum.  "Das  Receptaculum  ist 
von  einen  diinnen  Pflasterepithel  ausgekleidet,  aber  es  besitzt  eine 
dicke  fibrose  Wand,  die  reich  an  eingeschalteten  Kernen  ist." 
The  writer  cannot  distinguish  cell  walls  in  the  lining  of  the 
receptaculum,  but  finds  scattered  nuclei,  embedded  in  a  mass  of 
delicate  interlacing  fibres. 

The  receptaculum  seminis' contains,  embedded  in  the  mass  of 


1911 J  Watson:   The  Genus  Gyrocotyle.  399 

spermatozoa,  occasional  deeply  staining  cells,  large,  and  with 
very  large  nuclei.  These  were  noted  and  figured  by  Spencer 
(1889,  p.  146)  :  he  suggests  that  they  "may  be  simply  the  sperm- 
blastophores  from  which  the  ripe  sperm  have  separated^  but 
there  is  no  proof  of  this. ' '  The  writer  is  convinced  that  they  are 
ova,  which  have  entered  the  receptaculum  seminis  through  the 
duct  which  leads  from  this  structure  to  the  oviduct,  the  ductus 
seminalis.  The  finding  of  these  cells  at  the  entrance  of  this  duct 
into  the  receptaculum  and  their  resemblance  to  the  ova,  renders 
this  certain. 

The  passage  to  the  oviduct,  the  ductus  seminalis,  has  a  very 
thick  muscular  wall  lined  with  cilia  and  an  exceedingly  small 
lumen,  often  completely  obliterated  in  sections.  For  this  reason, 
Spencer  was  unable  to  demonstrate  it  to  his  own  satisfaction, 
though  convinced  that  it  must  exist. 

The  vagina  passes  forward,  in  the  early  part  of  its  course 
much  convoluted  and  lying  close  to  the  receptaculum  seminis. 
Further  forward  it  lies  in  the  parenchyma  close  to  the  dorsal 
wall  of  the  uterus ;  it  turns  ventrally  near  the  middle  of  its  course 
and  passes  gradually  to  the  ventral  surface,  where  it  finally 
opens,  laterally  and  posteriorly  to  the  penis,  near  the  right 
margin  of  the  body.  The  lumen  of  the  vagina  is  lined  with  a 
layer  similar  to  that  described  for  the  receptaculum  seminis,  not 
ciliated.  It  is  not  epithelial,  as  described  by  Lonnberg.  Its  wall 
is  composed  of  a  thin  layer  of  longitudinal  muscle  fibres ;  it  is 
embedded  in  parenchyma  and  lies  within  the  main  mass  of  longi- 
tudinal muscles,  close  to  the  wall  of  the  uterus.  As  the  vagina 
nears  the  anterior  margin  of  the  uterus  its  lumen  increases  in 
diameter.  During  its  course  past  the  convolutions  of  the  vas 
deferens  this  increase  continues,  and  its  wall  is  also  increased  in 
thickness.  The  lining  of  the  tube  becomes  much  convoluted 
in  its  course  toward  the  left  margin,  and  increases  suddenly  in 
diameter  in  the  latter  half  of  its  transverse  course,  opening 
finally  by  a  large  aperture  with  much-folded  margins  and  heavy 
muscular  wall.  This  region  is  plainly  adapted  to  copulation. 

The  testes  are  arranged  in  two  groups  not  connected  and  not 
symmetrical  (pi.  39,  fig.  42).  The  left  testis  extends  from  the 
posterior  border  of  the  anterior  third  of  the  body,  forward  to 


400"         University  of  California  Publications  in  Zoology.     tv°L-  6 

the  opening  of  the  penis.  The  right  testis  is  composed  of  two 
lobes,  the  right  and  larger  of  which  extends  from  the  posterior 
level  of  the  left  testis  forward  to  the  anterior  extremity  of  the 
body.  The  left  lobe,  attached  by  a  narrow  bridge  posterior  to 
the  base  of  the  acetabulum,  lies  to  the  left  of  the  acetabulum 
and  in  front  of  the  vaginal  opening.  The  testes  lie  within  the 
longitudinal  muscle  mass,  in  a  position  identical  with  that  occu- 
pied by  the  ovaries  in  the  posterior  portion  of  the  body.  They 
are  considerably  larger  than  the  ovaries,  as  is  shown  in  plate  39, 
figure  42,  and  are  composed  of  loosely-aggregated  follicles.  Each 
follicle  is  covered  with  a  fibrous  nucleated  layer,  the  "tunica 
propria"  of  Lb'nnberg,  continuous  with  the  walls  of  the  tubules 
into  which  the  follicle  opens.  These  unite  into  two  main  vasa 
efferentia  and  empty  into  a  large  median  vesicula  seminalis 
situated  immediately  in  front  of  the  uterus,  nearest  the  ventral 
surface.  This  structure  is  perhaps  more  accurately  described 
as  a  vas  deferens,  more  or  less  uniformly  dilated  by  the  masses 
of  spermatozoa.  It  coils  from  left  to  right  and  from  dorsal  to 
ventral,  in  three  large  convolutions  (pi.  41,  fig.  46),  dilating 
near  its  anterior  extremity  to  form  a  bulb,  and  opening  through 
a  muscular  papilla  into  a  thick-walled  tube,  the  cirrus-pouch  or 
ejaculatory  duct.  The  wall  of  this  pouch  is  thick  and  well  sup- 
plied with  muscles.  Its  inner  lining  is  greatly  folded  and  covered 
with  delicate  spinules.  This  duct  passes  almost  straight  dorsad, 
turning  a  little  to  the  left,  opening  on  a  rounded  papilla  on  the 
dorsal  surface,  a  little  to  the  left  of  the  median  line  and  anterior 
to  the  mouth  of  the  vagina  on  the  ventral  surface.  The  wall  of 
the  duct  grows  much  thinner  toward  its  distal  end  and  its  lumen 
increases  somewhat.  Heavy  bundles  of  muscle  fibres  running  at 
right  angles  to  the  course  of  the  ejaculatory  duct  are  attached 
to  its  wall  throughout  the  whole  of  its  course  (rad.  muse.  /.,  pi. 
43,  fig.  65).  Outside  these  lies  a  large  mass  of  gland-cells  extend- 
ing the  whole  length  of  the  ejaculatory  duct.  They  are  very  large 
granular  cells,  with  definite  cell-walls  forming  intracellular 
canals  (prost.  gL,  pi.  43,  fig.  64).  These  empty  into  numerous 
delicate  ducts  opening  on  the  surface  of  the  ejaculatory  duct 
and  probably  constitute  a  prostate  gland.  Outside  this  gland  lie 
heavy  longitudinal  muscle  bundles,  a  part  of  the  body  muse  u  In- 


1911]  Watson:   The  Genus  Gyrocotyle.  401 

ture.  The  cells  of  the  gland  are  embedded  in  the  innermost  of 
these  muscle-bundles.  The  lumen  of  the  ejaculatory  duct  is 
lined  with  a  thin  cuticula,  beneath  which  are  found  cuticular 
muscle  fibres  and  subcuticular  cells.  Outside  this  layer  is  a 
thick  mass  of  circular  muscle  fibres,  and  outside  these  a  heavy 
longitudinal  layer  of  fibres.  To  this  coat  are  attached  the 
radially  arranged  muscle  fibres  above  described",  inserting  in 
general  at  the  angle  shown  in  figure  65,  plate  43. 

Spermato genesis. — The  follicles  of  the  testes  are  lined  by  a 
syncytium  in  which  are  embedded  rather  small  rounded  nuclei 
of  the  spermatogonia.  The  middle  of  the  follicle  is  filled  with 
dividing  cells  and  developing  spermatozoa.  No  attempt  has  been 
?nade  to  work  out  the  details  of  the  process  of  spermatogenesis. 
It  may  be  mentioned  that  in  none  of  the  preparations  observed 
by  the  writer  were  there  any  indications  of  amitosis,  but  several 
mitotic  figures  were  observed.  The  mature  spermatozoon  is  a 
slender  thread  tapering  at  the  posterior  end,  with  a  well-marked 
head,  several  times  the  diameter  of  the  body  and  staining  in- 
tensely (pi.  41,  fig.  50). 

The  Ovum  and  Oogenesis. — Unfortunately  the  writer  has  seen 
no  young  specimens  of  Gyrocotyle.  While  there  has  been  great 
variation  in  size,  in  all  individuals  the  uterus  has  been  full  of 
developing  embryos  which  mark  the  specimens  as  sexually 
mature.  Lonnberg,  the  only  investigator  who  has  had  the  good 
fortune  to  work  with  the  immature  form,  described  the  ovaries 
in  the  young  individuals  as  follows : 

"Das  Ovarium  hat  bei  jiingeren  Individuen  eine  nicht  gewohnliche 
Gestalt,  indem  es  viel  mehr  traubig  gelappt  als  bei  anderen  Cestoden  1st. 
Es  besteht  also  in  diesem  Stadien  aus  kleinen  rundlichen  Follikeln,  die 
durch  weite  Ausfuhrungsgange  zu  Trauben  vereinigt  werden,  und  diese 
Trauben  erster  Ordnung  werden  durch  ihre  Ausfiihrungsgange  zu  Trauben 
zweiter  Ordnung  verbunden.  Alle  Trauben  vereinigen  sich  zu  je  einer 
Sammlung  aufschmelzen  aber  allmalig  die  Trauben  zu  unregelmassigen 
Lappen  zusammen  und  es  seheint  daher  nicht  treffend,  wenn  Spencer  auf 
seiner  schematischen  Figur  ein  so  distinkt  traubenfb'rmiges  Ovarium  bei 
einem  Tiere  mit  von  Eiern  prall  gefiillten  Uterus  zeichnet. " 

Spencer  (1889,  p.  144)  dealt  with  sexually  mature  forms,  but 
found  two  stages  of  reproductive  activity : 

"In  the  first-mentioned  the  ova  were  evidently  passing  down  into  the 
uterus,  in  which  they  were  but  very  slightly  developed.  The  ovaries 


402          University  of  California  Publications  in  Zoology.     [VOL-  6 

consequently  were  full  of  fully  formed  ova,  having  the  nature  of  distinct 
cells  with  clearly  defined  nuclei.  In  the  second  the  uterus  was  full  of 
much  more  highly  developed  embryos,  and  no  ova,  apparently,  were  pass- 
ing into  it.  In  this  case  the  ovaries  were  evidently  in  the  act  of  develop- 
ing a  fresh  supply  of  ova.  Each  consisted  of  a  mass  of  protoplasm  con- 
taining nuclei,  evidently  dividing  rapidly,  whilst  the  outlines  of  the  cells 
could  only  here  and  there  be  seen  with  anything  approaching  to  clearness. 
Each  little  ovary  has  thus,  when  the  ova  are  not  fully  formed,  the  struc- 
ture of  a  polynuclear  mass  of  protoplasm,  which  only  subsequently 
becomes  divided  up  into  a  number  of  distinct  cells. '  '1 

In  all  the  preparations  studied  by  the  writer,  the  ovaries  con- 
tained at  the  same  time  both  fully  formed  and  developing  ova; 
the  uterus  contained  young  embryos  in  its  most  posterior  coils, 
and  older  ones  towards  its  anterior  opening.  It  seems  that  in 
G.  fimbriata  the  process  of  egg  formation  goes  on  uninterruptedly 
the  year  round,  rather  than  in  a  rhythmical  fashion,  as  indicated 
for  G.  rugosa  by  Spencer 's  observations.  This  may  be  correlated 
with  the  fact  that  apparently  the  period  of  intra-uterine  life  is 
longer  in  G.  rugosa  than  in  any  other  species,  this  being  the  only 
form  in  which  the  uterus  contains  hooked  embryos. 

Each  follicle  of  the  ovary  is  surrounded  by  a  fibrous  layer, 
called  by  Lonnberg  the  "tunica  propria,"  continuous  with  the 
walls  of  the  oviducts  into  which  the  ova  are  discharged.  Plate 
41,  figure  52  represents  a  typical  follicle  with  ova  in  early  stages 
of  development.  There  is  a  syncytium  containing  small,  round 
nuclei  with  recticular  chromatin  and  either  a  very  small  nu- 
cleolus  or  none  whatever.  The  other  half  of  the  same  follicle  is 
cut  up  into  cells  with  definite  walls,  denser  cytoplasm,  clear 
nuclei  nearly  double  the  size  of  those  in  the  syncytium,  with 
dense  marginal  chromatin  reticulum  and  very  large  excentric 
nucleolus.  Plate  41,  figure  53  represents  stages  intermediate 
between  these  two,  showing  the  growth  of  the  nuclei  and  par- 
ticularly the  appearance  of  a  large  extra-nuclear  body,  staining 


i  Dr.  M.  Hungerbiihler's  "Studien  an  Gyrocotyle  und  Cestoden " 
(1910)  was  received  too  late  for  its  results  to  be  incorporated  in  the  body 
of  this  paper.  He  makes  the  suggestion,  based  on  the  facts  above  quoted 
mentioned,  that  Spencer  was  dealing  with  two  different  species  of  Gyro- 
cotyle, that  is,  with  G.  urna  and  G.  rugosa.  While  this  explains  numerous 
discrepancies  in  Spencer 's  account,  and  while  my  own  results  show  the 
presence  of  two  species  of  Gyrocotyle  in  one  species  of  Chimaera,  yet  the 
forms  described  by  Spencer  differ  widely  in  several  essentials  from  G. 
urna,  and  Hungerbiihler 's  grounds  for  concluding  that  one  of  Spencer's 
forms  was  G.  urna  do  not  seem  adequately  to  account  for  these  differences. 


Watson:   The  Genus  Gyrocotyle.  403 

by  most  methods  as  deeply  as  does  the  nucleus  but  easily  dis- 
tinguishable from  it  in  strongly  decolorized  haematoxylin 
preparations,  and  also  in  borax  carmine-Lyon 's  blue  prepara- 
tions. Plate  41,  figure  54  shows  the  origin  of  this  body  as  an 
extruded  nucleolus,  distinguishable  even  when  within  the  nuclear 
membrane  from  the  chromatin  nucleolus  proper.  Probably  only 
one  such  body,  or  * '  yolk-nucleolus, "  is  formed  during  the 
development  of  the  ovum.  In  fully  formed  ova  this  yolk- 
nucleolus  has  greatly  decreased  in  staining  intensity,  appearing 
as  a  mere  shadowy  ring  with  a  dark  center  (pi.  41,  fig.  51). 

The  ripe  ovum  passes  from  the  follicle  into  the  oviduct  where 
it  takes  on  an  irregular  elongated  form,  strongly  suggesting 
amoeboid  movements.  This  form  has  also  been  noted  by  Lonn- 
berg  (1891,  p.  40).  These  ova  are  the  largest  cells  in  the  body, 
measuring  about  26^,  by  15/A.  Their  cytoplasm  is  very  dense,  full 
of  shapeless  masses  of  material.  The  nuclei  are  about  12/A  in 
diameter,  clear,  with  heavy  deeply  staining  chromatin  reticulum 
and  large  round  nucleus,  from  5/x  to  6/x  in  diameter.  The  nu- 
cleolus is  larger  than  any  other  nucleus  in  the  body,  except  those 
of  the  ganglion  cells  of  the  first  order  and  possibly  the  nuclei  of 
yolk  cells.  The  large,  clear  bright  nucleus  with  its  dense  deep- 
staining  nucleolus  makes  the  ovum  easily  recognizable  even  under 
low  magnification. 

The  processes  of  maturation,  which  have  not  been  observed, 
probably  occur  after  the  ova  reach  the  receptaculum  ovorum. 
Division  of  oogonia  in  the  follicles  of  the  ovary  appears  to  take 
place  by  true  mitotic  division.  Equatorial  plates  and  anaphases 
have  been  observed,  but  no  attempt  has  been  made  to  work  out 
the  phases  of  mitosis.  There  are  no  indications  of  amitosis,  either 
here  or  in  the  follicles  of  the  testes.  It  seems  probable  from  the 
evidence  in  Gyrocotyle,  that  Child's  (1907)  amitotic  figures  are 
the  result  of  confusing  the  "yolk-nucleolus"  with  the  nucleus 
proper.  Such  figures  as  are  shown  in  plate  41,  figures  52,  53,  54, 
could  easily  be  taken  for  unequal  mitotic  divisions  of  the  nucleus, 
were  it  not  for  the  differential  staining. 

The  vitellaria  are  follicular,  each  follicle  being  surrounded 
by  a  fibrous  tunica  propria  as  in  ovary  and  testes.  The  early 
stages  of  yolk-cells  resemble  those  of  the  young  ova.  A  single 


404          University  of  California  Publications  in  Zoology.     tv°L-  6 

follicle  frequently  contains  a  great  variety  of  stages.  Near  one 
margin  are  found  scattered  nuclei  in  a  syncytium;  the  rest  of 
the  follicle  is  filled  with  cells  with  well-defined  walls  and  full  of 
yolk-spheres  (pi.  41,  fig.  49).  The  cells  are  large,  about  20/A, 
with  round  clear  nuclei,  dense  marginal  chromatin  and  a  round 
central  nucleolus.  The  cytoplasm  is  reduced  to  a  thin  marginal 
layer  in  which  the  nucleus  is  embedded.  The  body  of  the  cell  is 
packed  with  yolk-platelets,  from  %/*  to  2/u  in  diameter,  granular 
in  composition,  and  staining  rather  faintly  except  with  Lyon's 
blue  and  toluidin  blue,  with  both  of  which  the  platelets  stain 
very  intensely.  The  whole  cell  breaks  out  of  the  follicle  and 
enters  the  system  of  yolk-ducts,  through  which  it  makes  its  way 
to  the  yolk-reservoir  and  thence  to  the  uterus.  The  yolk-plates 
have  been  observed  by  me  only  within  a  nucleated  cell.  The  cell 
as  a  unit  becomes  one  of  the  components  of  the  compound  egg 
formed  in  the  uterus. 

This  statement  is  not  in  agreement  with  Lonnberg's  descrip- 
tion of  conditions  in  G.  urna.  He  says:  "Die  Dotterzellen  zer- 
f  all  en  schliesslich,  so  dass  nur  die  Kornchen  durch  die  Grange  zu 
den  Eizellen  gelangen. ' '  That  is,  only  the  yolk-platelets,  not  the 
yolk-cells  themselves,  enter  into  the  composition  of  the  uterine 
egg.  Aside  from  the  fact  that  yolk-ducts,  reservoir,  and  the 
beginning  of  the  uterus  are  all  full  of  typical  nucleated  yolk- 
cells,  the  most  cursory  examination  of  the  early  coils  of  the  uterus 
shows  that  the  eggs,  even  before  the  shell  is  completely  formed, 
are  multicellular.  Lonnberg  saw  this,  but  interpreted  it  as  evi- 
dence of  a  very  early  cleavage  of  the  ovum.  "Die  Eifurchung 
tritt  sehr  friihzeitig  ein,  so  dass  man  Eier  findet,  deren  Schalen 
noch  nicht  fertig  gebildet  sind,  aber  wo  das  Embryo  schon 
gebildet  ist. ' '  But  a  careful  examination  of  such  an  early  uterine 
egg  shows  that  it  contains  cells  of  two  kinds,  one  having  the 
characteristic  size,  staining  reactions  and  nuclear  structure  of 
the  ovarian  ovum  (ov.),  and  the  others  typical  vitellarian  cells 
(yk.  c.,  pi.  9,  fig.  47).  Cleavage  of  the  ovum  does  not  begin  for 
some  time  after  the  shell  is  completely  formed.  Spencer's  (1889, 
p.  145)  observations  concerning  the  yolk-gland  and  his  figures 
of  yolk-follicles  are  very  puzzling.  His  statements  are  as  follows : 

"A  difference  of  structure  has  been  noted  above  in  the  case  of  the 


Watson:   The  Genus  Gyrocotyle.  405 

ovaries  of  the  two  examples  examined,  containing  embryos  at  different 
stages  of  development  in  the  uterus,  and  a  curious  difference  obtains  also 
in  the  yolk-glands  of  the  two  forms.  In  the  one  containing  highly 
developed  embryos  the  yolk-glands,  like  the  ovaries,  are  evidently  provid- 
ing a  fresh  supply  of  material  in  prospect  of  the  next  period  of  repro- 
ductive activity.  Each  consists  of  a  mass  of  cells,  the  outlines~of~  which 
are  somewhat  more  clearly  marked  than  in  the  case  of  ovaries,  with  large 
nuclei  evidently  undergoing  division.  The  cells  are  remarkably  similar 
to  ova,  but  the  relative  size  of  the  yolk  masses  and  their  definite  super- 
ficial position  renders  them  distinct  from  the  ovaries.  In  the  case  of  the 
form  containing  the  ova  passing  down  into  the  uterus,  the  yolk-glands 
are  in  a  much  more  advanced  stage.  Each  is  filled  with  a  mass  composed 
partly  of  distinct  yellow  globular  bodies,  and  partly  of  nucleated  cells. 
So  far  as  can  be  seen  there  are  no  definite  "shell-glands'7  present;  all 
the  other  structures  connected  with  the  reproductive  organs  could  be 
distinctly  made  out  by  means  of  sections,  and  presumably  shell-glands 
would  have  been  able  to  be  recognized  if  they  were  present  as  distinct 
and  separate  structures.  In  plate  13,  figure  2,  is  represented  a  portion  of 
the  first  part  of  the  uterus,  in  which  evidently  the  shells  are  being 
formed  around  the  ova.  In  addition  to  nucleated  cells,  the  uterus  con- 
tains very  numerous  little  drop-like  yellow  structures,  which  resemble 
exactly  those  which  have  been  previously  described  as  present  in  the 
yolk-glands.  It  appears  as  if  these,  as  it  were,  "ran  together,"  and 
formed  a  case  enclosing  certain  of  the  nucleated  cells,  some  of  which  are 
ova,  and  some  probably  cells  from  the  yolk-glands  which  will  serve  as 
food  for  the  developing  ova.  This  appears  to  be  the  only  construction 
which  can  be  placed  upon  the  appearances." 

Failing  to  find  any  shell-glands  in  G.  rugosa,  Spencer's 
hypothesis  (though  not  definitely  stated  to  be  such)  seems  to  be 
that  both  shell-material  and  yolk-platelets  are  formed  in  the  yolk- 
glands,  as  indicated  in  his  plate  13.  Nothing  resembling  this 
type  of  follicle,  or  indicating  such  a  function  of  the  vitellaria, 
has  been  seen  in  G.  fimbriata.  It  is  hard  to  believe  that  Spencer 
could  have  observed  so  delicate  and  obscure  a  structure  as  the 
network  of  yolk- ducts  in  the  region  of  the  receptaculum  seminis, 
and  overlooked  the  large  and  unmistakable*  masses  of  the  shell- 
glands,  had  they  been  present  in  G.  rugosa.  Lonnberg  (1891), 
who  observed  the  shell-glands  in  G.  urna,  suggests  that  Spencer 
mistook  the  central  mass  of  the  shell-glands  for  the  central  part 
of  the  ovary.  This  suggestion  is  rendered  less  plausible  by  the 
fact  that  the  main  mass  of  the  shell-glands  lies,  not  in  the  median 
line,  but  laterad  of  the  receptaculum  seminis,  and  is  simply 
ma'rked  off  from  the  mass  of  the  ovaries.  A  revision  of  Spencer 's 
material  seems  to  be  the  only  way  in  which  the  discrepancy  in 
observations  can  be  explained. 


406          University  of  California  Publications  in  Zoology.     ITOL-  6 

V.  FORMATION  OP  THE  COMPOUND  EGG  AND  CLEAVAGE 
OP  THE  OVUM. 

The  formation  of  the  compound  egg  of  Gyrocotyle  in  the  first 
coils  of  the  uterus  has  been  described  above.  The  completed 
egg  presents  the  appearance  shown  in  plate  41,  figure  47,  taken 
from  the  fifth  coil  of  the  uterus.  Cleavage  begins  very  shortly ; 
at  the  same  time  the  walls  of  the  yolk  cells  become  less  definite 
and  their  nuclei  fainter.  There  is  no  indication  of  cleavage  of 
the  yolk-cells.  The  mass  of  cells  resulting  from  cleavage  of  the 
ovum  appears  to  be  a  syncytium  (pi.  41,  fig.  48)  ;  this  mass 
increases  in  size  with  the  diminution  of  the  yolk  cells.  It  is 
impossible  to  make  out  cell  walls  or  to  discover  any  orderly 
arrangement  of  the  nuclei,  in  the  preparations  available.  The 
eggs  cannot  be  made  sufficiently  transparent  for  study  in  toto; 
and  the  shells  are  so  resistant  that  no  successful  infiltration  with 
paraffme  was  obtained.  The  best  preparations,  and  the  ones  on 
which  these  statements  and  figures  are  based,  were  celloidin  sec- 
tions stained  with  Delafield's  hematoxylin.  The  egg-shells  show 
no  opercula,  and  no  trace  of  hooks  on  the  embryo  could  be  dis- 
cerned. G.  rugosa  seems  to  be  the  only  member  of  the  genus 
which  possesses  hooked  embryos  in  uterine  eggs. 

The  eggs  when  extruded  are  surrounded  by  a  gelatinous  sub- 
stance which  forms  a  jelly  on  contact  with  sea-water.  They  are 
discharged  with  considerable  force.  The  discharge  has  been 
observed  repeatedly  when  the  intestine  of  the  host  was  first  slit 
open,  and  also  when  the  animal  was  changed  from  one  solution 
to  another.  Eggs  are  always  found  in  the  intestinal  contents 
of  Chimaera  infected  with  Gyrocotyle.  The  eggs  when  first  dis- 
charged are  white  and  glistening,  resembling  finely  cut  sand- 
grains.  They  are  about  .095  mm.  by  .065  mm.  and  ellipsoidal  in 
shape.  The  size  varies  widely  in  eggs  from  the  same  individual, 
discharged  at  the  same  time,  ranging  from  .075  mm.  to  .112  mm., 
in  longest  dimension. 

The  newly  discharged  eggs  do  not  possess  opercula  (pi.  38, 
fig.  41).  There  is  a  faint  differentiation  occasionally  seen  at  one 
pole  of  the  egg,  but  nothing  which  could  be  definitely  identified 
as  an  operculum  has  ever  been  found  in  fresh  eggs.  In  speci- 


1911]  Watson:   The  Genus  Gyrocotyle.  407 

mens  which  had  begun  to  decay  in  the  intestines,  and  in  prepara- 
tions made  by  Von  Rath's  method,  a  perfectly  definite  and 
clearly  marked  operculum  was  found  (operc.,  pi.  38,  figs.  38,  39, 
40).  This  does  not  appear  to  be  comparable  to  the  operculum 
figured  by  Haswell  (see  my  plate  47,  figure  81)*.  Its  margins  are 
finely  toothed,  and  the  shell  is  somewhat  thinner  in  the  opercular 
cap  than  elsewhere. 

VI.  EXCRETORY  SYSTEM. 

The  network  of  excretory  canals,  so  richly  developed  in 
Gyrocotyle,  is  one  of  the  first  features  to  strike  the  eye  in  obser- 
vation of  the  living  animal.  Wagener  (1851)  saw  and  described 
it,  and  noted  particularly  its  wonderfully  elaborate  development. 
The  excretory  system  consists  of  the  following  parts :  ( 1 )  "  flame- 
cells, "  (2)  capillaries,  (3)  excretory  canals  distributed  outside 
the  inner  longitudinal  muscle  layer,  (4)  excretory  canals  lying 
within  and  among  the  fibres  of  the  inner  longitudinal  muscles. 

The  "flame-cells"  (pi.  43,  figs.  62,  63)  are  large,  with  swollen 
base  in  which  lies  an  oval  nucleus  with  rich,  deeply-staining 
chromatin  reticulum.  The  surrounding  cytoplasm  is  granular, 
occasionally  vacuolated,  and  stains  as  heavily  as  does  that  of  the 
gland-cells.  Running  apparently  from  the  apex  of  the  nucleus  is 
a  fine  thread,  extending  for  some  distance  through  the  hollowed- 
out  body  of  the  cell.  Each  flame-cell  thus  forms  an  intracellular 
canal,  which  leads  into  a  capillary.  These  flame-cells  are  found 
only  in  the  outer  layers  of  the  body  in  what  has  been  described 
as  the  "intermediate"  region,  within  the  subcuticular  layers  and 
outside  the  inner  longitudinal  muscle  mass.  Neither  Spencer 
(1889)  nor  Wagener  (1852)  found  any  such  structures;  Lonn- 
berg  (1891)  found  them,  but  tells  us  nothing  about  them,  except 
that  they  lie  in  the  "  Rinden-schicht. " 

The  capillaries  are  the  fine  tubules  into  which  the  intra- 
cellular ducts  of  the  flame-cells  lead.  They  have  very  thin  walls, 
and  differ  from  the  excretory  canals  in  not  having  a  cuticular 
lining  or  a  muscle  layer.  They  are  found  throughout  the  body 
wherever  flame-cells  appear. 

The  excretory  canals  lying  outside  the  inner  longitudinal 
muscle  mass  differ  from  those  lying  within  this  layer  chiefly  in 


408          University  of  California  Publications  in  Zoology.     [VOL.  6 

size.  They  are  lined  with  a  cuticula  resembling  that  covering 
the  body,  and  are  surrounded  by  a  well-developed  band  of  cir- 
cular muscle  fibres  (circ.  muse.  I.,  pi.  11,  fig.  60)  resembling  in 
size  and  shape  the  cuticular  longitudinal  fibres  of  the  body.  Out- 
side of  this  circular  muscle  layer  is  a  mass  of  parenchyma  fibres 
passing  in  the  same  direction.  Nuclei  are  scattered  about  irregu- 
larly in  the  neighborhood  of  this  layer,  but  often  at  some  little 
distance  from  it. 

In  the  larger  of  these  canals,  a  large  tuft  of  cilia  projects 
into  the  lumen,  through  a  break  in  the  cuticular  lining,  running 
the  whole  length  of  the  canal.  These  ciliated  canals  receive  the 
smaller  non-ciliated  ones.  The  non-ciliated  canals  are  plainly  to 
be  seen  in  the  living  animal  in  the  lateral  frills,  in  close  relation 
to  the  follicles  of  the  vitellaria,  emptying  on  the  one  side 
(lateral)  into  a  small  non-ciliated  "sinus  terminalis"  (Wag- 
ener)  and  on  the  other  side  (medial)  into  a  ciliated  canal  of 
about  twice  their  own  diameter  (pi.  35,  fig.  20).  Still  further 
mediad,  near  the  base  of  the  lateral  folds,  is  a  second  ciliated 
canal,  of  the  same  size  and  appearance  as  the  first.  In  it,  how- 
ever, the  waves  of  motion  traverse  the  cilia  in  the  opposite  direc- 
tion from  that  taken  in  the  more  lateral  canal.  Thus,  if  in  the 
outer  one  waves  pass  from  anterior  to  posterior,  in  the  inner  one 
they  run  from  posterior  to  anterior.  The  motion  is  almost  in- 
credibly swift  and  very  regular. 

The  largest  excretory  canals  lie  within  the  central  core  of  the 
body,  among  the  inner  longitudinal  muscles,  the  ovaries  and 
testes.  Running  the  length  of  the  body,  on  either  side  of  the 
uterus,  is  a  very  large  ciliated  canal,  the  largest  in  the  body.  The 
structure  of  these  canals  is  like  that  of  the  smaller  peripheral 
canal  described  above,  except  that  the  lining  is  thicker,  the  muscu- 
lar layer  better  developed  and  nuclei  more  numerous  in  the  neigh- 
borhood of  the  wall  of  the  canal.  In  no  case  has  it  been  possible 
to  recognize  any  connection  between  the  cilia  of  the  canals  and 
the  neighboring  nuclei,  such  as  was  figured  by  Lonnberg  (1891, 
Taf.  3,  figs.  39,40). 

Around  the  anterior  margin  of  the  acetabulum  there  is  a 
fairly  well-defined  ring-canal,  receiving  many  small  anastomos- 
ing longitudinal  branches.  Its  diameter  and  relations  shown 


Watson:  The  Genus  Gyrocotyle.  409 

by  sections  do  not  indicate  that  it  is  connected  with  the  central 
canal-system,  but  rather  with  the  peripheral  non-ciliated  system 
of  the  lateral  folds.  The  same  is  true  for  the  dense  network 
of  non-ciliated  canals  found  in  the  posterior  rosette.  This  rosette 
region  is  riddled  through  and  through  with  small  carialsV  much 
like  capillaries  in  size  and  structure  of  wall.  No  flame-cells 
appear  in  this  region.  A  ring-canal  appears  in  the  "neck,"  at 
the  level  of  the  canal  opening.  Like  the  acetabular  ring,  this 
appears  to  be  immediately  connected  with  the  peripherally 
situated  canals,  and  through  them  with  the  deeper-lying  larger 
vessels  (ant.  ex.  r.,  pi.  36,  fig.  26.) 

In  several  specimens  a  dilation  of  one  of  the  large  longitudinal 
canals  has  been  found  in  the  region  of  the  vaginal  opening,  usu- 
ally posterior  to  it.  These  dilations  take  the  form  of  a  thin- 
walled  sphere,  into  which  the  large  canal  empties,  containing 
droplets  of  a  structureless  yellow  material.  It  is  certain  that 
this  "bladder"  is  not  a  constantly  occurring  structure.  No 
external  openings  have  ever  been  found,  except  by  Spencer 
(1889)  on  G.  rugosa :  "  Wagener  was  unable  to  find  any  external 
opening  of  the  excretory  system,  but,  after  long  searching,  I  have 
been  able  to  find  two  unmistakable  openings  on  the  ventral  sur- 
face, one  on  either  side  of  the  body,  slightly  in  front  of  the  open- 
ing of  the  uterus  to  the  external  surface."  Lonnberg  (1891) 
was  unable  to  find  these  openings ;  the  writer  has  never  seen  them. 
But  it  seems  highly  probable  that  these  temporary  "bladders" 
may  burst  through  the  wall  of  the  body  to  form  a  temporary 
external  opening,  closing  up  after  the  collapse  of  the  * '  bladder, ' ' 
due  to  the  discharge  of  its  contents. 

VII.  NERVOUS  SYSTEM. 

The  nervous  system  of  Gyrocotyle  is  of  great  interest  with 
reference  to  the  problem  of  orientation,  both  in  the  genus  itself 
and  in  merozoic  cestodes.  It  may  be  divided  into  central  and 
peripheral  parts,  according  to  the  muscle  layers  with  which  the 
nerve  stems  are  related.  The  sense  in  which  the  phrase  "central 
nervous  system"  is  used  is  of  course  quite  distinct  from  the 
meaning  usually  attached  to  it  when  applied  elsewhere,  as  for 
example  to  vertebrates.  Neither  should  this  use  of  the  term  be 


410          University  of  California  Publications  in  Zoology.     [VoL-  <> 

confused  with  that  advocated  by  Cohn  (1898)  for  merozoic  ces- 
todes.  He  believes  that  all  of  the  longitudinal  nerves,  together 
with  their  transverse  connections  in  scolex  and  proglottides,  con- 
stitute the  central  nervous  system.  The  branches  from  these  to 
the  various  organs  and  to  the  surface  of  the  animal  he  regards 
as  the  peripheral  system.  While  all  the  evidence  indicates  that 
such  a  division  would  be  justifiable  in  Gyrocotyle,  it  is  not  in  this 
sense  that  the  terms  are  here  used,  but  purely  with  reference  to 
position,  not  at  all  with  reference  to  structure  or  function. 

The  peripheral  nervous  system  consists  of  eight  longitudinal 
stems,  lying  in  the  intermediate  muscle  layers,  just  outside  the 
outer  longitudinal  set  of  fibres,  and  communicating  with  the  cen- 
tral system  by  means  of  the  anterior  nerve  ring  around  the  mar- 
gin of  the  acetabulum.  There  are  no  ganglion  cells  in  these 
strands;  they  are  very  small  and  exceedingly  difficult  to  trace. 
With  borax  carmin  and  Lyon's  blue  they  stain  a  very  clear  light 
blue,  and  can  be  recognized  with  some  ease  in  the  neighborhood  of 
the  acetabulum,  especially  near  their  junction  with  the  anterior 
ring.  These  strands  have  not  been  previously  described.  They 
innervate  the  intermediate  muscle  layers  (outer  transverse  and 
outer  longitudinal),  wherever  these  occur  in  the  body  proper, 
in  the  inner  layers  of  the  acetabulum,  and  in  the  inner  layers  of 
the  funnel. 

In  dealing  with  the  central  system  it  is  important  to  remem- 
ber and  recognize  the  existence  of  these  extra-central  nerves,  for 
it  is  only  when  the  central  system  is  clearly  distinguished  from 
the  others  that  the  relations  of  its  parts  become  intelligible.  It  is 
perhaps  because  of  their  failure  to  take  account  of  this  division 
that  the  results  of  investigators  of  the  nervous  system  of  Gyro- 
cotyle have  shown  so  little  agreement  in  details. 

It  is  hardly  necessary  to  say  that  the  study  of  the  nervous 
system  by  means  of  serial  sections,  already  made  difficult  by  the 
great  contractility  of  the  body,  is  rendered  a  much  more  serious 
problem  by  the  necessity  of  dealing  not  with  two  stems,  their 
branches  and  connectives,  but  with  six  or  perhaps  ten  such  stems. 
To  determine  whether  a  complete  ring  is  present  in  any  part  of 
the  body  becomes  a  task  of  serious  difficulty,  and  indeed  one  im- 
possible without  the  assistance  of  the  relations  of  the  different 


1911]  Watson:   The  Genus  Gyrocotyle.  411 

sets  of  nerves  to  the  muscle  layers,  which  can  always  be  distin- 
guished from  one  another. 

The  central  nervous  system  lies  within  (mediad  to)  and 
among  the  inner  longitudinal  muscle-fibres,  and  within  (mediad 
to)  the  large  longitudinal  excretory  canals.  It  consists  of  the 
following  parts : 

1.  Two  lateral  longitudinal  stems. 

2.  An  anterior  bridge  commissure  and  an  anterior  ring  com- 
missure, in  the  acetabular  region. 

3.  A  posterior  bridge  and  two  ring  commissures,  joined  by 
eight  longitudinal  connectives. 

The  nervous  system  was  first  recognized  by  Wagener  (1852), 
who  saw  only  the  anterior  commissure.  Monticelli  (1889a)  and 
Spencer  (1889)  recognized  the  posterior  commissure.  According 
to  Spencer,  this  commissure  is  continuous  around  the  canal,  form- 
ing a  complete  ring  surrounding  the  canal ;  the  dorsal  half  of  the 
commissure  extending  farther  posterior  than  the  ventral  half. 
According  to  Monticelli  this  is  not  the  case.  He  found  that  on 
the  ventral  surface  the  two  parts  did  not  unite,  but  merely  ran 
alongside  each  other,  then  separating  passed  posteriorly,  each 
ending  independently  in  the  margin  of  the  "Trichter. "  Both 
these  investigators  agree  in  placing  the  anterior,  heavy  and  in- 
dubitable part  of  the  commissure  on  the  same  surface  as  the 
canal  opening,  i.e.,  the  ventral  face  (dorsal  of  Spencer  and  Monti- 
celli). This  puts  the  anterior  (acetabular)  commissure  on  the 
opposite  surface  from  the  posterior  (scolex)  commissure. 

Lonnberg  (1891)  described  both  commissures  as  lying  on  the 
ventral  surface.  He  found  the  posterior  commissure  to  be  a 
bridge,  not  a  complete  ring,  posterior  to  which  the  longitudinal 
stems  are  continuous  to  the  margin  of  the  funnel,  where  each 
breaks  up  into  many  branches,  which  probably  form  by  their 
anastomoses  a  ring  about  the  margin  of  the  funnel  opening. 
Thus  his  account  differs  from  Monticelli 's  in  (1)  the  presence 
of  a  marginal  ring  at  the  posterior  extremity,  and  ( 2 )  the  absence 
of  any  statement  of  the  near  approximation  of  the  posterior 
nerve  stems  to  each  other  posterior  to  the  commissure.  It  differs 
from  Spencer  in  the  first  point,  and  also  in  the  absence  of  any 
indication  of  the  completion  of  the  posterior  commissure  to  form 


412          University  of  California  Publications  in  Zoology.     [V°L-  6 

a  ring  surrounding  the  canal.  Lonnberg  also  differs  from  Spen- 
cer and  Monticelli  in  placing  the  posterior  commissure  "ven- 
trally. "  The  apparent  contradiction  in  these  results  is  due  to 
incomplete  rather  than  erroneous  observation. 

The  longitudinal  nerve  stems  or  lateral  connectives  (long.  n. 
st.,  pi.  39,  fig.  42)  lying  in  the  dorsal  half  of  the  central  region 
of  the  body,  run  from  the  anterior  to  the  posterior  commissure. 
They  are  separated  from  each  other  by  one-third  of  the  width 
of  the  body  in  the  anterior  quarter  of  the  body,  but  spread 
further  apart  at  the  level  of  the  birth  pore,  lying  near  the  lateral 
margins  of  the  uterus.  In  the  region  of  the  ovaries  they  ap- 
proach the  median  line  again.  Each  stem  gives  off  two  sets  of 
branches,  one  in  the  sagittal  and  the  other  in  the  horizontal  plane. 
These  branches  are  heaviest  and  most  profuse  in  the  regions  of 
the  ovaries  and  the  testes. 

The  acetabular  nervous  system  consists,  as  elsewhere  in  the 
body,  of  a  central  and  peripheral  portion.  The  peripheral  system 
comprises  eight  longitudinal  strands  with  many  anastomosing 
branches.  These  strands  innervate  the  peripheral  muscle  layers 
of  the  body,  and  the  homologous  muscle  layers  of  the  acetabulum. 
They  come  into  relation  with  the  central  nervous  system  by 
means  of  the  anterior  ring  in  the  margin  of  the  acetabular  open- 
ing (acet.,  pi.  39,  fig.  42.) 

The  central  system  includes  an  anterior  bridge  commissure, 
lying  just  in  front  of  the  posterior  margin  of  the  acetabulum  on 
its  dorsal  surface ;  a  pair  of  anterior  lateral  stems  with  branches ; 
and  an  anterior  nerve  ring  (pi.  39,  fig.  42).  The  commissure 
forms  a  bridge  between  the  two  longitudinal  nerve  stems.  There 
is  a  ganglionic  enlargement  of  the  lateral  stem  at  a  point  where 
it  is  joined  by  the  bridge  commissure.  The  commissure  is  in  the 
shape  of  an  arch,  enlarged  at  the  ends  and  smaller  in  the  middle 
of  its  course.  Its  mass  with  respect  to  the  rest  of  the  body  varies 
widely,  perhaps  with  the  state  of  contraction  of  the  animal ;  it  is 
fairly  constant  with  respect  to  the  nervous  system  as  a  whole. 
No  branches  are  given  off  from  the  commissure  itself.  The  mar- 
ginal ganglionic  knots  are  about  double  the  diameter  of  the 
lateral  stem  (ant.  br.  comm.,  pi.  39,  fig.  42).  They  are  enlarge- 
ments of  the  lateral  stems,  beginning  at  the  point  where  the 


1911]  Watson:  The  Genus  Gyrocotyle.  413 

anterior  bridge  commissure  is  given  off  and  reaching  their  great- 
est size  in  that  region.  Anteriorly  they  pass  into  the  anterior 
longitudinal  stems,  extending  fully  a  third  of  the  total  distance 
from  the  commissure  to  the  anterior  ring.  From  eaeh_ganglion 
the  following  branches  are  given  off  (pi.  36,  fig.  27). 

1.  An   anterior   lateral   nerve   stem,    a   prolongation   of   the 
anterior  nerve  stem  in  front  of  the  anterior  bridge  commissure, 
runs  forward  along  the  dorso-lateral  margins  of  the  acetabulum. 
From  these  stems  there  are  given  off  dorsal,  ventral  and  lateral 
branches  to  the  body  musculature,  and  median  branches  to  the 
outer  coat  of  the  acetabular  muscles.   Certain  branches  from  the 
dorsal  surface  run  forward,  to  the  dorsal  sensory  ridges  later 
described,  and  from  the  ventral  surface  of  each  stem  near  its 
anterior  extremity  a  large  nerve  runs  forward  ventro-laterally  to 
the  sensory  pits  on  the  ventral  serface.  At  the  anterior  extremity 
of  the  worm  near  the  acetabular  opening,  each  lateral  nerve  stem 
divides  into  two  branches  which  pass,   one  ventrad,  the  other 
dorsad,  at  right  angles  to  the  longitudinal  stem.     These  nerves 
break  up  in  the  median  line  to  form  the  anterior  nerve  ring. 

2.  Four  nerves  are  given  off  from  the  ventral  surface  of  the 
knot,  two  of  which  are  directed  posteriorly  and  two  anteriorly. 
The  posteriorly  directed  pair  of  branches  are  distributed  to  the 
follicles  of  the  testes   (test,  n.,  pi.  36,  fig.  27).     The  anteriorly 
directed  pair  pass  around  the  posterior  margin  of  the  acetabulum 
on  its  ventral  surface  and  send  out  branches  on  this  surface. 

3.  Four  nerves  arise  from  the  dorsal  surface,  running  for- 
ward and  laterally  into  the  inner  longitudinal  muscles. 

4.  Two  nerves  arise  from  the  lateral  surface  of  the  ganglion, 
one  running  forward  and  ventrally,  the  other  towards  the  dorsal 
surface,  into  the  central  musculature  of  the  body  and  the  vitel- 
laria. 

5.  Several  nerves  are  given  off  from  the  anterior  face  of  the 
ganglion  and  run  forward  along  the  surface  of  the  acetabulum 
to  innervate  the  outer  meridional  acetabular  muscle  coat    (the 
homologue  of  the  inner  longitudinal  coat  of  the  body  muscula- 
ture). 

The  Anterior  Ring   Commissure. — The  anterior  end  of  the 
worm  is  pierced  by  a  round   opening  into   the   cavity   of   the 


414          University  of  California  Publications  in  Zoology.     [VOL.  6 

acetabulum.  The  circular  margin  of  this  opening  is  rounded  and 
thick,  due  to  the  presence  of  a  heavy  sphincter.  Surrounding 
this  opening,  within  the  sphincter  of  the  margin,  is  the  anterior 
excretory  ring  and  the  anterior  nerve  ring.  This  is  formed  as 
described  by  dorsal  and  ventral  terminal  branches  of  the  anterior 
lateral  stems,  united  in  the  median  line  by  a  dorsal  and  ventral 
anastomosis.  This  ring  is  thus  composed  laterally  of  a  single 
large  nerve,  but  in  the  median  line  of  many  small  anastomosing 
threads  (pi.  39,  fig.  42).  In  its  lateral  portions  at  the  points  of 
junction  with  the  lateral  nerve  stem,  there  is  a  slight  enlarge- 
ment in  which  typical  ganglion  cells  are  present.  From  the  ring 
are  given  off  nerves  ramifying  in  the  margin  of  the  acetabular 
opening,  and  in  the  outer  layer  of  the  acetabular  muscle  coat. 
The  ring  also  receives  the  peripheral  stems  mentioned  above. 

The  Central  Nervous  System  of  the  Rosette  and  Canal. — The 
posterior  rosette  may  be  considered  as  composed  of  two  parts, — 
a  funnel  and  a  canal.  The  wide-mouthed  funnel  with  glandular, 
much  folded  walls  is  circular  in  cross-section,  and  roughly  V- 
shaped  in  sagittal  section,  the  point  of  the  V  being  directed 
anteriorly.  That  is  to  say,  the  course  of  the  funnel  tube  is  almost 
straight  forward  through  the  center  of  the  body  (pi.  46,  fig.  76). 
Its  posterior  margin  is  bordered  by  the  frills  which  make  up  the 
posterior  rosette.  At  the  base  of  these  frills  there  is  a  thickening 
of  the  walls  of  the  funnel  commonly  referred  to  as  the  neck  of 
the  rosette,  due  to  the  formation  of  a  sphincter  by  the  inner 
transverse  muscle.  This  funnel  leads  into  the  canal,  a  narrow, 
non-glandular  region,  passing  a  little  anteriorly  and  almost 
directly  ventrad  to  open  on  the  ventral  surface  of  the  valve-like 
canal  opening.  The  region  where  the  canal  joins  the  funnel, 
the  apex  of  the  V,  will  be  called  the  tope,  from  the  corresponding 
region  of  an  ordinary  funnel.  The  walls  of  the  canal  itself  show 
no  central  innervation.  There  are  apparent  fine  fibres  of  the 
intermediate  and  cuticular  nerves  but  no  branches  of  the  central 
system.  From  the  tope  of  the  funnel  posteriorly  the  walls  of  the 
passage  are  weakly  innervated  by  a  complicated  set  of  commis- 
sures, stems,  and  branches,  all  belonging  to  the  central  system. 
consisting  of  the  following  parts : 

1.  A  posterior  bridge  commissure  connecting  laterally  situ- 
ated ganglionic  knots. 


1911]  Watson:   Tlie  Genus  Gyrocotyle.  415 

2.  A  proximal  ring  commissure  directly  connected  with  the 
posterior  margin  of  the  ganglionic  knots. 

3.  A  distal  ring  commissure,   connected  with  the  proximal 
ring  by  eight  connectives. 

4.  Anastomoses  between  these  connectives  in  the  lateral  walls 
of  the  funnel. 

5.  Eight  branches  running  posteriorly  from  the  distal  ring 
commissure  into  the  folds  of  the  terminal  rosette. 

The  main  longitudinal  stems  lie  as  above  noted  in  the  dorsal 
half  of  the  central  region.  At  a  point  just  posterior  to  the  tope, 
close  to  the  wall  of  the  funnel,  each  stem  enlarges  to  form  a 
ganglionic  knot  (pi.  35,  fig.  17).  These  knots  are  connected 
dorsally  by  a  transverse  bridge  which  is  fairly  large  laterally, 
but  narrows  to  the  merest  thread  in  the  median  region,  not  dis- 
tinguishable with  a  magnification  of  less  than  300  diameters. 
The  ganglionic  knots  at  the  ends  of  this  bridge  commissure  pass 
diagonally  across  the  lateral  walls  of  the  cavity.  This  forms  the 
"bow-commissure"  of  Spencer.  Each  ganglionic  knot  divides 
into  two  main  branches,  a  dorsal  and  a  ventral,  which  pass 
toward  the  median  line  to  join  similar  branches  from  the  opposite 
side,  thus  forming  the  proximal  ring  commissure,  lying  about 
half-way  between  the  neck  or  sphincter  region  and  the  tope  of 
the  funnel.  It  was  probably  the  ventral  half  of  this  ring  which 
Spencer  regarded  as  forming  the  "dorsal"  region  of  his  bow- 
commissure,  embracing  the  funnel.  Lonnberg's  "ventral"  com- 
missure was  probably  the  dorsal  half  of  this  same  ring,  plus  the 
lateral  ganglionic  knots  of  the  posterior  commissure,  the  half- 
ring  and  knots  being  connected  by  one  of  the  primary  lateral 
connectives  to  be  described  later.  The  middle  third  of  the  dorsal 
posterior  bridge  commissure  is  so  delicate  that  it  is  easily  over- 
looked. However,  the  continuity  and  independence  of  both  the 
dorsal  commissure  and  the  dorsal  half  of  the  ring  can  be  easily 
demonstrated  in  serial  sections  with  a  magnification  of  about  300 
diameters. 

In  the  neck  or  sphincter  region  there  is  formed  a  second  ring 
which  completely  encircles  the  posterior  margin  of  the  funnel  at 
the  base  of  the  frills.  This  posterior  ring  is  connected  with  the 
proximal  ring  by  eight  connectives  (lat.  long,  conn.,  pi.  35,  fig. 


416          University  of  California  Publications  in  Zoology.     [V°L-  6 

17).  Of  these,  the  two  lateral  pairs  are  derived  from  the  primary 
longitudinal  stems,  each  divided  into  two  and  continued  pos- 
teriorly from  the  ganglionic  knots.  The  two  lateral  connectives 
of  each  side  are  interconnected  by  anastomosing  branches,  lateral 
and  irregular,  nearly  parallel  to  the  proximal  ring,  and  fre- 
quently quite  as  heavy.  The  dorsal  and  ventral  median  pairs, 
lying  in  the  median  third  of  the  funnel  wall,  extend  only  from  the 
proximal  ring  to  the  distal  ring.  From  the  distal  ring  branches 
run  out  into  the  frills  at  the  points  where  the  longitudinal  con- 
nectives enter  the  ring. 

Distribution  of  Ganglion  Cells. — No  attempt  has  been  made 
to  deal  with  the  histology  of  the  nervous  system,  further  than 
is  necessary  for  understanding  the  significance  of  the  structure  of 
the  ganglionic  knots  at  the  lateral  margins  of  the  anterior  and 
posterior  commissures.  The  nerve  stems,  both  longitudinal  and 
peripheral,  are  composed  of  exceedingly  delicate  fibrils,  woven 
together  in  a  dense  meshwork  (pi.  34,  fig.  16).  Around  the  stem 
is  a  covering  of  nucleated  parenchyma  fibres,  or  sheath  cells. 
There  are  no  nuclei  within  the  meshwork.  At  intervals  along  the 
two  main  lateral  stems,  where  branches  are  given  off,  there  appear 
just  inside  these  ''sheath  cells"  a  cluster  of  cells  having  homo- 
geneous cytoplasm  and  oval,  clear  nuclei,  with  a  few  chromatin 
nucleoli  (gang.  1st.,  pi.  44,  fig.  67).  These  correspond  to  the 
"first  type"  of  ganglion  cells  described  by  Pintner  (1880)  and 
by  Niemiec  (1886).  They  occur  only  at  the  margins  of  the  main 
lateral  nerve  stems  and  in  the  nerve  rings :  the  anterior  ring,  the 
proximal  and  distal  ring  commissures.  In  the  ganglion  knots 
there  occur  very  large  cells,  with  coarsely  granular,  intensely 
staining  cytoplasm,  and  a  large,  clear  nucleus  containing  one 
large  and  several  small  chromatin  nucleoli  (pi.  44,  fig.  66) .  With 
Lyon  's  blue  these  cells  stain  a  dark  violet  blue  quite  distinct  from 
the  clear  "Himmelblau"  as  Lonnberg  calls  it,  of  the  the  fibrous 
tissue.  These  occur  only  in  the  ganglion  knots  of  the  anterior 
and  posterior  bridge  commissures,  not  at  all  in  the  median  sec- 
tions of  the  commissures,  in  the  rings,  or  lateral  stems.  They  are 
not  numerous,  their  total  number  not  exceeding  seventy  or  eighty. 
They  correspond  to  the  second  type  of  cells  described  by  Pintner 
and  by  Niemiec,  commonly  referred  to  as  giant  cells. 


1911]  Watson:  The  Genus  Gyrocotyle.  417 

VIII.  SENSE  ORGANS. 

The  presence  of  sensory  end-organs  in  cestodes  has  been 
several  times  suggested,  but,  never  established  to  the  satisfaction 
of  investigators  in  general.  Lang  (1891)  says  "The  cestodes  no 
longer  possess  any  specific  sensory  organs."  Braun  (1894)  in 
Bronn's  Thierreich  (p.  1300)  quotes  Blumberg  (1877)  as  observ- 
ing nerve  endings  in  the  limiting  membrane  or  cuticle  of  the 
Taenia  of  horses.  These  endings  are  in  the  form  of  delicate 
threads  terminating  in  a  swollen  knob.  Braun  thinks  that,  con- 
sidering Zernecke  's  observations,  it  seems  probable  that  Blumberg 
saw  actual  nervous  end-organs.  Linton  (1891)  briefly  describes 
an  organ  of  hearing  in  Otobothrium  crenacolle,  as  a  small  struc- 
ture covered  with  hairs,  situated  on  the  bothridia.  Beyond  these, 
and  Schiefferdecker 's  (1874)  interpretation  of  flame-cells  as 
nerve  endings;  there  are  no  references  to  sense-organs  in  the 
literature  of  cestodes,  in  so  far  as  that  is  known  to  the  writer. 

In  Gyrocotyle  the  whole  acetabulum  functions  much  as  does 
the  proboscis  of  the  rhabdocoelan  Proboscidea,  as  a  highly 
efficient  organ  of  exploration,  or  one  might  say  of  touch.  While 
the  whole  surface  of  the  acetabulum  is  richly  innervated,  there 
are  on  the  margin  of  the  opening  of  the  acetabulum  two  ridges 
with  a  peculiar  and  significantly  rich  nerve  supply,  and  two  shal- 
low pits  in  which  lie  flat  plates  of  nervous  tissue,  end-organs  of  a 
pair  of  heavy  branches  from  the  anterior  lateral  stem  above 
referred  to. 

1.  The  Sensory  Ridges  or  Papillae. — These  lie  one  on  each 
side  of  the  latero-dorsal  margin  of  the  acetabular  opening.      A 
nerve  from  the  anterior  lateral  stem  spreads  out  within  each 
"papilla,"  its  branches  running  to  the  base  of  the  very  thin 
limiting  membrane. 

2.  The  Sensory  Pits    (sens,  pits,  pi.   36,   figs.    23,    25)     lie 
farther  laterad  than  the  papillae,  and  on  the  opposite  or  ventral 
surface  of  the  acetabular  margin.     They  consist  of  a  definite 
depression,  covered  with  a  differentiated  membrane,  immediately 
beneath  which  lies  a  plate  of  nervous  tissue,  formed  by  a  very 
heavy  branch  from  the  anterior  longitudinal  nerve.     This  does 
not  break  up  but  ends  abruptly  as  a  plate  of  nervous  tissue 


418          I'  Diversity  of  California  Publications  in  Zoology.     tv°L-  6 

immediately  beneath  the  limiting  membrane  of  the  pit.  These 
pits  stain  an  intense  blue  when  the  living  animal  is  treated  with 
methylen  blue.  They  take  up  the  stain  quickly  and  hold  it  for 
several  hours  after  removal  from  the  staining  medium.  The 
function  of  these  pits  is  totally  unknown,  but  the  presence  of 
central  nervous  tissue  immediately  beneath  their  surface  indicates 
their  possession  of  some  sensory  function. 

E.  GENERAL    DISCUSSION. 

This  investigation  was  undertaken  and  carried  out  in  the  hope 
of  obtaining  evidence  which  would  definitely  settle  the  question 
of  antero-posterior  orientation.  This  evidence  was  sought  along 
three  lines:  (1)  morphological  relationships  of  organs,  in  them- 
selves and  compared  with  other  platyhelminths ;  (2)  behavior  of 
the  living  animal;  (3)  embryological  history.  The  writer  has 
unfortunately  failed  to  find  any  extra-uterine  embryological 
material,  and  has  no  evidence  from  this  source  to  offer.  The  fact 
that  Chimaera  colliei  can  not  be  kept  in  aquaria,  even  large  ones, 
with  any  measure  of  success  (Dean,  1906,  p.  16)  makes  the  life- 
history  a  hard  problem  to  attack.  I  am  convinced  that  we  have 
thus  far  no  hint  whatever  as  to  the  intermediate  host  of  Gyro- 
cotyle.  The  occurrence  of  decaying,  sexually  mature  forms  in 
Mactra  edulis  has,  it  seems,  no  bearing  on  this  question.  The 
youngest  forms  reported,  the  only  immature  ones  in  fact,  are  the 
young  individuals  found  by  Lonnberg  in  the  spiral  valve  of  C. 
monstrosa.  This  fact  indicates  that  the  worm  enters  the  host  in 
a  sexually  immature  condition.  The  fact  that  no  hatched  em- 
bryos have  been  found  in  the  intestinal  contents  of  Chimaera 
indicates  that  Gyrocotyle,  like  other  cestodes,  has  at  least  two 
hosts.  Further  than  this  we  know  nothing  of  its  life-history.2 

Conclusive  morphological  and  functional  evidence  bearing  on 
the  question  of  orientation  has  been  found  in  abundance.  In  the 
course  of  this  work,  evidence  bearing  on  certain  other  questions 


2  The  discovery  by  Hungerbiihler  (1910)  of  cysticercoids  in  the  paren- 
chyma of  Gyrocotyle  rugosa  is  a  recent  addition  to  our  knowledge  of  the 
embryology  of  the  genus.  The  embryo  resembles  the  ten-hooked  embryo 
already  figured  by  Spencer  as  an  extra-uterine  embryo.  Its  position  (near 
the  uterine  pore)  suggests  that  the  wall  of  the  uterus  may  have  given  way 
in  that  region  in  the  preparation  of  the  specimen. 


1911]  Watson:   The  Genus  Gyrocotyle.  419 

of  interest  to  students  of  the  phylum  has  been  found;  this  will 
be  briefly  discussed  before  proceeding  to  consider  the  main  prob- 
lems of  orientation. 

I.    CUTICULA. 

The  question  of  ectodermal  origin  of  the  "cuticula"  or  limit- 
ing membrane  of  the  body,  and  the  significance  of  the  "sub- 
cuticular  cells ' '  in  the  trematodes  and  cestodes  has  been  recently 
reviewed  by  Professor  Pratt  (1909).  Blochmann's  theory,  re- 
garding the  subcuticular  cells  as  a  sunken  epithelial  layer,  and 
the  limiting  membrane  as  a  true  cuticula,  such  as  is  found  in 
arthropods  and  annelids,  Pratt  considers  completely  discredited 
by  various  pieces  of  embryological  and  morphological  evidence. 
He  considers  the  "cuticula"  to  be  nothing  but  a  closely  matted 
layer  of  parenchyma  fibres,  from  which  the  nuclei  have  dis- 
appeared. The  observations  made  on  Gyrocotyle  seem  to  bear 
out  this  view  of  the  limiting  membrane.  Of  particular  interest 
are  the  conditions  of  the  vagina,  receptaculum  seminis  and 
uterus.  Here  the  lining  of  these  ducts  is  in  direct  continuity 
with  the  cuticula  at  their  openings ;  there  is  a  gradual  transition 
from  this  cuticular  lining  to  one  of  comparatively  loose-matted 
fibres  and  indefinite  boundaries,  containing  unmistakable  paren- 
chyma nuclei  and  passing  on  its  inner  surface  indistinguishably 
into  a  typical  parenchymatous  net  in  which  lie  muscle  fibres. 
This  same  transition  can  be  seen  on  the  inner  surface  of  the  folds 
of  the  posterior  rosette.  Furthermore,  nowhere  in  Gyrocotyle 
have  I  found  a  definite  layer  of  epithelial  cells.  Such  tissue, 
described  by  Lonnberg  for  the  ducts  of  the  reproductive  system, 
resolves  itself  in  favorable  preparations  and  under  high  magni- 
fication into  the  dense  parenchymatous  layer,  fibrillated  and 
without  cell-walls,  above  described. 

One  statement  made  by  Pratt  in  support  of  this  view  of  the 
cuticula  as  not  associated  with  the  subcuticular  cells  is  not  borne 
out  by  conditions  in  Gyrocotyle.  He  says:  "If  now  the  cuticula 
is  the  product  of  the  underlying  subcuticular  cells,  we  should 
expect  to  find  some  special  development  of  them  beneath  the 
hooks  and  spines,  especially  where  these  are  very  large,  just  as 
in  the  integument  of  insects  a  cuticular  hair  or  scale  is  invariably 


420          University  of  California  Publications  in  Zoology.     [VOL-  6 

situated  over  the  enlarged  hypodermal  cell  which  produces  it. 
Nothing- of  the  sort  exists  in  trematodes  and  cestodes.  The  sub- 
cuticular  cells  beneath  the  hooks  and  spines  do  not  differ  in  size, 
number  or  arrangement,  from  the  adjacent  cells  and  in  the 
monogenetic  trematodes,  which  are  often  provided  with  gigantic 
hooks,  no  subcuticular  cells  at  all  are  present." 

In  Gyrocotyle  the  subcuticular  layer  of  cells  is  much  increased 
in  thickness  in  the  neighborhood  of  a  spine  and  is  closely  related 
to  it. 

A  question  of  far  greater  difficulty  is  that  of  the  function  of 
the  subcuticular  cells.  If  not  related  to  the  formation  of  the 
cuticula,  what  is  their  function?  Pratt  makes  two  suggestions; 
first  that  they  are  secretory  in  function,  forming  an  antibody 
for  the -protection  of  the  worm  from  the  chemical  action  of  the 
medium  in  which  it  lives.  This  is  supported  by  the  fact  that 
these  cells  are  altogether  lacking  in  monogenetic  trematodes.  A 
second  suggestion  (see  Looss,  1894),  is  that  these  cells  constitute 
an  undifferentiated  embryonic  layer,  from  which  new  cells  of 
various  tissues  are  formed  during  the  lifetime  of  the  animal. 
The  only  evidence  in  support  of  this  theory  is  the  statement  that 
in  certain  individuals  known  to  be  of  advanced  age,  the  sub- 
cuticular layer  was  greatly  reduced. 

The  glandular  theory  finds  no  definite  support  in  the  con- 
ditions in  Gyrocotyle.  The  unmistakable  gland  cells  here  present 
are  found  as  above  noted  in  the  central  core  of  the  body,  not 
in  relation  to  the  peripheral  layer.  The  statement  made  by 
previous  investigators  that  the  subcuticular  layer  gives  rise  on 
the  inner  surface  of  the  rosette  folds  to  gland  cells  has  not  been 
verified  in  the  writer's  preparations.  However,  this  does  not 
militate  against  the  possible  glandular  nature  of  these  cells.  The 
intense  staining  reaction  of  the  cytoplasm  of  at  least  some  of 
these  cells  recalls  the  appearance  presented  elsewhere  by  un- 
mistakable gland  cells. 

Looss 's  suggestion  seems  hardly  susceptible  of  proof  or  dis- 
proof. It  is  difficult  to  believe  that  the  layer  of  cells  so  closely 
related  in  position  to  the  cuticula,  varying  in  thickness  with  its 
thickness  and  increasing  in  the  region  of  special  cuticular  struc- 
tures such  as  spines,  should  be  totally  unrelated  to  the  body- 


1911]  Watson:  The  Genus  Gyrocotyle.  421 

covering.  The  conditions  of  Gyrocotyle  indicate  very  clearly 
that  the  subcuticular  layer  is  related  to  the  cuticular  muscula- 
ture, and  that  some  at  least  of  its  cells  are  to  be  considered  the 
myoblasts  of  the  cuticular  muscles.  There  is  much  in  the  litera- 
ture of  the  subject  in  harmony  with  this  suggestion ;  Blochmann 
(1896)  shows  in  his  diagrammatic  cross-section  of  Ligula  myo- 
blasts lying  near  the  subcuticular  layer.  He  was  able  to  distin- 
guish these  cells  from  the  rest  of  the  subcuticular  layer.  This  the 
writer  is  unable  to  do  in  Gyrocotyle.  The  fact  that  the  cuticular 
musculature  always  increases  with  the  thickness  of  the  cuticula, 
disappearing  as  the  cuticula  thins  out  and  passing  into  the 
fibrous  nucleated  layer  above  described,  lends  support  to  the 
suggestion.  In  the  lining  of  the  receptaculum  seminis  and  the 
posterior  end  of  the  vagina,  no  subcuticular  cells  can  be  seen. 
These  ducts  are  surrounded  by  simple  nucleated  muscle  fibres. 
In  the  early  coils  of  the  uterus,  where  this  same  nucleated 
fibrous  lining  is  found  but  where  cilia  are  also  present,  the  cilia 
pass  through  the  fibrous  layer  and  are  in  connection  with  scat- 
tered nuclei  lying  just  beneath  the  fibrous  lining.  Further 
along  the  course  of  the  uterus,  where  a  definite  non-nucleated 
fibrous  lining  has  appeared,  beneath  which  lies  a  cuticular  mus- 
culature, the  subcuticular  layer  appears,  just  as  it  does  beneath 
the  cuticular  musculature  of  the  body-covering.  All  the  facts 
available  indicate  that  at  least  a  large  part  of  the  subcuticular 
cells  are  related,  not  to  the  cuticula,  but  to  the  cuticular  muscu- 
lature as  myoblasts.  The  subcuticular  cells  in  the  neighborhood 
of  the  spines  are  probably  related  to  the  protractor  musculature 
of  these  structures. 

II.  ORIENTATION. 

The  question  of  antero-posterior  orientation  of  cestodes  is 
one  of  peculiar  difficulty.  Their  endoparasitic  and  attached 
mode  of  life  makes  it  impossible,  in  general,  to  settle  the  matter 
by  the  test  ordinarily  applied,  that  of  the  direction  of  locomo- 
tion. The  usual  custom,  reflecting  the  influence  of  Leuckart,  has 
been  to  regard  the  scolex  end  as  anterior,  the  free  end  as  pos- 
terior. Many  early  workers,  among  them  Perrier,  Grassi,  and 
Blanchard,  reversed  this  orientation,  looking  on  the  scolex  as 


422          rnircrsity  of  California  Publications  in  Zoology.     [VOL-  6 

the  posterior  end.  In  the  Cestodaria,  conflicting  views  as  to  the 
orientation  of  the  various  genera  have  long  existed,  and  in  the 
genus  Gyrocotyle  the  question  never  has  been  conclusively 
settled.  It  is  of  peculiar  importance  for  the  problem  of  cestode 
orientation  in  general  that  these  relations  should  be  well  estab- 
lished in  Gyrocotyle,  for  there  is  no  functional  antero-posterior 
orientation  in  the  adult  merozoic  cestode  and  the  problem  there 
is  one  of  comparative  morphology  and  phylogenetic  develop- 
ment. Since  Gyrocotyle  is  in  every  respect  a  primitive,  rela- 
tively simple  form,  parasitic  in  one  of  the  most  ancient  of 
vertebrates,  it  seems  reasonable  to  assume  that  this  cestode  may 
give  some  hint  as  to  the  extremity  at  which  the  ancestral  cestode 
most  probably  developed  its  organ  of  firm  attachment.  Observa- 
tions of  the  living  animal  have  shown  that  in  Gyrocotyle  there 
is  still  a  definite  functional  antero-posterior  orientation,  due  to 
the  fact  that  it  is  not  a  permanently  attached  form  but  is  still 
capable  of  locomotion. 

Diesing  (1855)  regarded  the  acetabular  end  of  Gyrocotyle 
as  anterior,  but  his  grounds  for  this  decision  are  not  clear. 
Working  with  a  few  poorly  preserved  specimens,  he  had  little 
on  which  to  base  his  conclusions.  Wagener  (1852),  who  did 
careful  work  on  the  living  animal  and  on  sections,  had  proposed 
the  same  orientation  on  the  basis  of  the  active  exploring  move- 
ments of  the  acetabulum  in  the  living  animal,  and  of  the  loca- 
tion of  a  bridge  commissure  of  the  central  nervous  system  at  the 
base  of  the  acetabulum.  This  orientation  was  followed  by  suc- 
ceeding investigators  up  to  Spencer  (1889),  who  reversed  it  on 
the  strength  of  the  discovery  of  a  similar  and  much  heavier  bow- 
commissure  at  the  rosette  extremity.  He  did  not  observe  living 
material.  Lonnberg,  working  on  a  large  quantity  of  living  and 
preserved  material,  followed  Spencer  in  regarding  the  rosette  as 
anterior,  basing  this  decision  on  the  behavior  of  the  living  animal 
(the  stretching  out  of  the  rosette  and  funnel  into  a  long  canal 
which  performed  exploring  movements  and  is  directed  forward 
in  locomotion,  according  to  his  observation),  on  the  great  de- 
velopment of  its  nervous  system  in  the  funnel  region,  and  the 
greater  abundance  of  ganglionic  cells  in  that  as  compared  with 
the  acetabular  commissure,  on  the  direction  of  the  spinules, 


1911]  Watson:   The  Genus  Gyrocotyle.  423 

which  point  toward  the  acetabulum;  and  also  on  the  fact  that 
the  worm  is  always  attached  to  the  rosette  extremity,  since 
"cestodes  always  attach  by  the  head  end."  Haswell  (1902) 
rejects  Lonnberg's  and  Spencer's  view  on  orientation  on  the 
basis  of  homologies  in  position  between  the  reproductive  organs 
of  Gyrocotyle  and  of  merozoic  cestodes,  to  which  in  his  opinion 
it  is  very  closely  related.  "The  end  which  bears  the  sucker  is 
seen  as  the  result  of  such  a  comparison,  to  correspond  to  the 
scolex  end  in  the  segmented  cestode."  This  homology  I  regard 
as  unjustifiable,  as  will  be  pointed  out  later.  Benham  (1891), 
comparing  the  reproductive  organs  of  Gyrocotyle  with  those  of 
Amphilina  and  the  heterocotylean  trematodes,  concludes  that  the 
acetabulum  of  Gyrocotyle  corresponds  to  the  anterior  sucker  of 
the  trematodes,  while  the  rosette  organ  and  its  peculiar  proboscis 
possibly  represents  the  posterior  caudal  disc  of  the  latter  class. 
An  examination  of  the  literature  of  the  genus  thus  shows 
that  the  orientation  of  Gyrocotyle  has  been  made  on  the  follow- 
ing grounds : 

1.  Behavior  of  living  animal. 

2.  Cephalization  of  the  nervous  system. 

3.  Homologies  of  the  reproductive  organs  with  similar  struc- 
ture in  the  merozoic  cestodes  and  in  the  trematodes. 

4.  Direction  of  spines. 

Conclusions  based  on  a  consistent  and  constant  functional 
orientation  of  the  living  animal  in  locomotion  and  general  move- 
ments are  unquestionably  well  grounded.  Conclusions  resting 
on  the  cephalization  of  the  nervous  system  assume  that  the 
nervous  system  will  be  centralized  and  most  richly  developed  in 
the  head  region.  This  is  true  for  worms  in  general  and  for  all 
platyhelminths  which  retain  in  any  marked  degree  the  power  of 
moving  from  place  to  place.  In  the  trematodes  there,  takes 
place,  however,  a  remarkable  development  of  ring-commissures 
in  connection  with  the  development  of  powerful  organs  of  attach- 
ment. This  is  especially  noticeable  in  the  large  posterior  termi- 
nal sucker  of  the  heterocotylean  trematode  (pi.  47,  fig.  79).  It 
seems  very  probable  that  in  a  permanently  attached  form,  like 
the  cestode,  in  which  the  most  powerful  and  highly  specialized 
musculature  of  the  body  is  centered  in  the  organ  of  attachment, 


424          University  of  California  Publications  in  Zoology.     [VOL-  6 

there  will  be  found  in  that  region  the  greatest  and  most  highly 
developed  mass  of  the  nervous  system,  quite  independent  of 
whether  the  attached  end  is  the  homologue  of  the  ancestral 
anterior  or  cephalic  extremity  or  not.  Therefore,  I  am  inclined 
to  question  conclusions  as  to  orientation  based  on  "cephaliza- 
tion"  of  the  nervous  system,  unless  confirmed  by  other  unques- 
tioned evidence. 

The  third  basis  on  which  the  question  has  been  decided,  the 
homologizing  of  the  reproductive  organs  and  openings  with  those 
of  trematodes  or  merozoic  cestodes,  can  obviously  only  be  applied 
in  the  direction  of  trematodes  as  long  as  the  orientation  of 
merozoic  cestodes  themselves  is  in  question.  Furthermore, 
antero-posterior  relations  among  these  structures  are  fixed  and 
constant  for  trematodes ;  while  among  cestodes  the  most  astonish- 
ing variations  present  themselves. 

The  direction  of  the  spines  is  not  at  all  a  decisive  piece  of 
evidence  inasmuch  as  spines  may  be  quite  as  useful  to  the  animal 
if  directed  anteriorly  and  serving  as  a  means  of  attachment,  as 
if  directed  posteriorly  and  serving  as  aids  to  locomotion. 

Wagener's  orientation  of  Gyrocotyle,  regarding  the  aceta- 
bulum  as  anterior,  the  rosette  as  posterior,  is  justified  in  my 
opinion  on  the  following  grounds: 

1.  This  is  the  functional  orientation  of  the  living  worm.    The 
rosette  end  is  relatively  quiescent  while  the  acetabular  end  is 
exceedingly  active  in  exploring  movements,  is  directed  anteriorly 
in  well-defined  progressive  locomotion,  and  leads  in  all  righting- 
up  movements.    The  rosette  end  never  leads  in  locomotion  except 
when  shoved  backward  by  the  doubling  under  of  the  active 
acetabular  end,  and  performs  no  movements  other  than  a  slight 
rolling  from  side  to  side.     This  mode  of  behavior  agrees  with 
that  described  by  Wagener   (1852)   in  his  original  account  of 
Gyrocotyle  urna;  but   is  totally  at  variance   with   Lonnberg's 
(1891)    observations  on  the  same   form.     This  discrepancy  is 
discussed  above. 

2.  The  position  of  the  reproductive  openings  in  Gyrocotyle 
as  compared  with  that  in  the  heterocotylean  trematodes  homo- 
logizes  the  rosette  with  the  posterior  sucker.     The  birth-pore  of 
Gyrocotyle  is  probably,  according  to  Goto's  (1891)  view  of  the 


1911]  Watson:   The  Genus  Gyrocotyle.  425 

uterus  in  cestodes,  the  homologue  of  the  female  copulatory  duct 
in  the  Heterocotylea ;  and  the  vagina  is  the  homologue  of  the 
heterocotylean  uterus.  This  gives  exactly  similar  anterior  and 
posterior  relations  to  the  openings  of  the  ducts,  the  penis-open- 
ings being  very  slightly  anterior  to  the  vaginal  opening~and  the 
birth-pore  lying  most  posteriorly  and  some  distance  to  one  side 
of  the  other  two. 

3.  Further  morphological  evidence  in  support  of  this  orienta- 
tion may  be  adduced  as  follows :  In  the  first  place  there  are  two 
pairs  of  abundantly  innervated  antero-lateral  sensory  areas,  com- 
parable in  structure  and  location  to  similar  areas  in  planarians 
and  certain  heterocotylean  trematodes.  In  the  second  place  the 
structure  of  the  central  nervous  system,  when  compared  with 
that  of  the  heterocotylean  trematodes,  affords  morphological  sup- 
port to  this  orientation.  The  anterior  commissure,  giving  off 
sensory  branches,  the  main  and  secondary  longitudinal  nerve 
strands,  the  eight  posterior  branches  and  a  posterior  ring  com- 
missure are  all  common  and  similarly  placed  in  Gyrocotyle  and 
the  heterocotylean,  as  for  example  in  Tristomum  molae,  whose 
nervous  system  was  described  by  Lang  (1882),  (pi.  47,  fig.  79). 
There  is  added  in  Gyrocotyle  the  delicate  median  portion  of  the 
bridge  commissure  and  the  second  ring  commissure,  which  may 
well  have  arisen  in  Gyrocotyle  in  correlation  with  the  increased 
mass  and  complexity  of  the  musculature  of  the  posterior  organ 
of  attachment,  the  rosette.  Thus  a  comparison  of  the  nervous 
system  and  the  position  and  innervation  of  the  organ  of  attach- 
ment of  Gyrocotyle  with  the  heterocotylean  compels  us  to  homolo- 
gize  the  rosette  with  the  posterior  sucker  of  the  trematode. 

The  development  of  two  bridge  commissures  at  the  two  ex- 
tremities of  the  body,  approximately  equal  in  abundance  of 
ganglion  cells  but  the  anterior  supplied  with  a  well-developed 
median  part  which  is  very  faint  in  the  posterior  one,  indicates 
the  manner  in  which  the  evolution  of  the  nervous  system  of  the 
merozoic  cestode  has  taken  place.  This  is,  briefly,  by  the  de- 
generation of  the  anterior  commissure  associated  with  the 
reduction  in  the  locomotor  and  sensory  functions  of  the  animal, 
and  the  great  development  of  the  posterior  commissure  and  its 


426          University  of  California  Publications  in  Zoology.     [V°L-  6 

stems  and  rings,  associated  with  the  development  of  the  powerful 
musculature  of  the  organ  of  attachment,  the  scolex. 

That  this  is  in  harmony  with  the  course  of  development 
elsewhere  in  the  phylum  is  shown  by  consideration  of  the 
probable  construction  of  the  nervous  system  of  the  primitive 
turbellarian-like  ancestor  and  the  changes  it  has  undergone. 
Throughout  the  phylum  there  is  remarkable  uniformity  in  the 
ground-plan  of  the  nervous  system.  The  primitive  structure  in 
the  free-living  Turbellaria  is  a  sub-dermal  plexus  of  fibres  and 
ganglion  cells  with  a  marked  concentration  of  these  at  the 
anterior  end,  and  an  increase  in  their  number  and  size  on  the 
ventral  or  creeping  surface.  This  differentiates  in  two  direc- 
tions ;  first  in  the  segregation  from  the  plexus  of  from  six  to  eight 
longitudinal  strands,  with  irregular  transverse  connecting  fibres ; 
and  second,  in  the  increase  in  size  of  the  main  bridge-commissure 
or  brain,  and  in  the  development  of  secondary  commissures  in 
the  region  of  the  brain  and  in  the  neighborhood  of  specially 
developed  musculature,  notably  in  the  pharynx  and  in  organs  of 
attachment.  This  is  to  be  seen  in  the  remarkable  development 
of  the  posterior  commissure  in  the  heterocotylean  in  connection 
with  the  development  of  the  posterior  sucker  as  the  principal 
organ  of  attachment.  Further,  two  of  the  longitudinal  nerve- 
strands,  the  ventral,  become  more  highly  developed  than  the 
rest.  In  the  trematodes  there  are  two  longitudinal  strands,  con- 
nected near  the  anterior  extremity  b}^  a  bridge-commissure  rich 
in  ganglion  cells  from  the  region  of  which  arises  a  pair  of  sensory 
nerves.  There  are  in  addition  numerous  peripheral  longitudinal 
strands  and  an  indefinite  number  of  cross-nerves,  anastomosing 
among  themselves  to  form  irregular  ring-commissures  about  the 
body.  In  the  posterior  region,  in  close  relation  to  the  large 
sucker,  is  developed  a  complicated  system  of  commissures  and 
rings.  From  this  type  the  nervous  system  of  Gyrocotyle  has 
been  derived.  The  longitudinal  strands  are  the  same  in  both; 
there  are  however  two  bridge-commissures  in  Gyrocotyle.  But 
the  sensory  function  of  the  acetabulum  and  the  forward  direc- 
tion of  that  extremity  in  locomotion,  together  with  the  well- 
developed  nature  of  that  commissure  throughout  as  compared 


1911]  Watson:   The  Genus  Gijrocotyle.  427 

with  the  delicate  median  thread  of  the  rosette  bridge-commis- 
sure, all  point  to  its  unmistakable  homology  with  the  anterior 
commissure  of  trematodes,  and  so  with  the  typical  "brain"  of 
the  Turbellaria. 

The  posterior  commissure  with  its  accompaniments'" of  com- 
plicated rings  and  connectives  has  plainly  been  developed  in  con- 
nection with  the  musculature  of  the  funnel-shaped  rosette-scolex. 
This  complex  development  of  nervous  structure  in  connection 
with  a  highly  developed  musculature  is  strikingly  shown 
throughout  the  phylum.  The  ventral  nerve  stems,  in  connection 
with  the  ventral  creeping  muscles,  become  heavier,  more  pro- 
fusely branched,  than  their  homologues  near  the  dorsal  surface. 
The  great  complexity  of  the  nervous  system  connected  with  the 
posterior  sucker  of  the  heterocotylean  has  already  been  referred 
to.  The  development  of  a  posterior  commissure,  in  itself  rather 
weak,  but  surrounded  by  a  complex  system  of  rings  and  connec- 
tives such  as  is  found  in  the  rosette  of  Gyrocotyle,  is  exactly 
what  would  be  expected  in  connection  with  the  development  of  a 
complicated  and  powerful  organ  of  attachment. 

The  comparison  of  the  nervous  system  of  Gyrocotyle  with 
that  of  the  merozoic  cestodes  shows  two  main  longitudinal  stems 
in  both.  These  are  more  or  less  sharply  differentiated  but  always 
sufficiently  clearly  marked  to  be  distinguished  from  the  weaker 
longitudinal  stems,  of  which  there  are  four  or  eight,  correspond- 
ing to  the  eight  peripheral  nerves  of  Gyrocotyle.  Near  the  free 
margin  of  the  proglottid,  which  must  be  regarded  as  anterior, 
these  longitudinal  stems  are  connected  by  a  transverse  commis- 
sure, in  close  connection  with  the  transverse  canal  of  the 
excretory  system.  In  the  scolex  there  is  a  heavy  ganglionic 
bridge-commissure,  joining  the  longitudinal  stems,  lying  midway 
between  the  dorsal  and  ventral  surfaces  of  the  body.  Peripheral 
to  this  and  in  contact  with  it  only  at  the  points  where  the  longi- 
tudinal stems  enter  the  commissures,  is  a  more  or  less  complete 
ring-commissure.  This  ring  reaches  its  most  perfect  develop- 
ment in  the  Taeniadae,  but  is  present  in  an  incomplete  form  in 
Ligula,  in  the  Tetrarhynchidae,  and  in  the  Tetraphyllidea. 
Distal  to  this  commissure  and  ring  is  found  a  more  or  less  clearly 
developed  ring  joined  to  the  former  by  numerous  connectives, 


428          University  of  California  Publications  in  Zoology.     [VOL-  6 

usually  six  or  eight  in  number.  This  ring  appears  in  a  rudi- 
mentary form  in  the  Tetraphyllidea  and  in  the  Tetrarhynchidae ; 
it  is  well  established  and  clearly  marked  in  the  Taeniadae  and 
the  Dibothridiata. 

It  is  at  once  evident  that  the  nervous  system  of  the  rosette 
in  Gyrocotyle  is  much  more  easily  homologized  with  the  nervous 
system  of  the  merozoic  cestode  scolex  than  is  the  nervous  system 
of  the  acetabular  region.  There  are  two  serious  objections  to  at- 
tempting to  derive  the  nervous  system  of  the  cestode  scolex  from 
the  acetabular  bridge-commissure  and  its  anterior  rings.  In  the 
first  place,  the  rosette  and  funnel  constitute  an  efficient  organ  of 
attachment,  so  strikingly  like  the  scolices  of  many  Tetraphyllidea 
in  mode  of  adhesion  and  probable  developmental  history — being 
formed  by  partial  fusion  of  the  walls  of  a  trough,  and  later  dif- 
ferentiation of  the  ends  of  the  tube  thus  formed — that  it  seems 
irrational  to  suppose  that  two  structures  of  such  fundamental 
similiarity  could  have  been  developed  independently  in  two 
groups  of  organisms  as  closely  allied  as  are  the  merozoic  and 
the  monozoic  cestodes.  The  acetabulum,  on  the  contrary,  never 
functions  as  a  sucker  or  organ  of  attachment;  there  seems  to  be 
no  possible  relationship  between  this  structure  and  any  of  the 
familiar  types  of  cestode  scolex.  There  is  every  reason,  on  the 
basis  of  function,  derivation  and  structure  for  regarding  the 
rosette  as  a  scolex  of  the  phyllidian  type.  In  the  second  place, 
there  is  no  "starting-point"  for  the  formation  of  a  ring  about 
the  acetabular  commissure,  no  matrix  out  of  which  to  differentiate 
the  complex  rings  and  connectives  of  the  nervous  system  of  the 
scolex.  Such  a  matrix  is,  however,  afforded  by  the  numerous 
anastomosing  branches  and  the  two  irregular  rings  and  their  con- 
nectives, seen  in  the  rosette  extremity. 

These  facts,  with  other  considerations  previously  given, 
justify  the  homologizing  of  the  scolex  of  the  merozoic  cestode 
with  the  rosette  of  Gyrocotyle,  a  posteriorly  situated  organ  of 
attachment.  This  conclusion  implies  a  functional  reversal  of  the 
nervous  system  of  the  ancestral  flatworm  in  the  course  of  its 
development  into  a  merozoic  cestode.  The  greatest  mass  of 
nervous  tissue,  cephalized  in  the  primitive  flatworm,  comes  to  lie 
in  the  posterior  region  of  attachment  of  the  cestode.  The  anterior 


1911]  Watson:   The  Genus  Oyrocotyle.  429 

commissure  disappears  and  the  ring  grows  weak  with  the  assump- 
tion of  the  sessile  habit  and  the  disappearance  of  sense-organs; 
while  the  posterior  commissure  develops  with  the  increase  in 
efficiency  and  complexity  of  the  organ  of  attachment. 

The  orientation  of  cestodes  here  suggested  has  been  advanced 
by  several  investigators,  on  more  or  less  substantial  grounds, 
from  Perrier  to  the  present  day.  This  contention  has  been  based 
for  the  most  part  on  embryological  evidence,  especially  with 
reference  to  the  hexacanth  onchosphaeres  so  characteristic  of 
cestodes.  The  well-established  fact  that  the  embryonic  hooks 
are  at  the  extremity  of  the  cysticercus  opposite  to  the  one  on 
which  the  organ  of  attachment  is  developed,  and  the  further  fact 
that  the  hook-bearing  part  of  the  onchosphaere  is  directed  for- 
wards in  the  movement  of  the  embryo,  affords  good  ground  for 
seriously  questioning,  if  not  altogether-  denying,  the  generally 
accepted  identification  of  the  scolex  as  "head."  Barrois  (1889) 
maintains  that  the  anterior  part  of  the  scolex  is  that  extremity 
which  bears  the  embryonic  hooks;  that  this  part  of  the  scolex 
gives  rise  to  the  first  proglottis,  which  is  therefore  to  be  regarded 
as  the  '  *  Kopf theil ' '  of  the  primitive  animal.  Furthermore,  the 
establishment  of  a  zone  of  growth  in  the  "neck"  of  the  strobila 
suggests  very  strongly  the  penultimate  "zone  of  growth"  in 
annelids,  with  which  the  "neck"  of  the  cestode  is  homologized 
if  the  scolex  is  recognized  as  posterior.  A  full  presentation  of  the 
evidence  in  favor  of  this  orientation,  derived  from  embryological 
and  comparative  anatomical  considerations  such  as  the  above, 
was  given  by  Cohn  (1907).  He  remarks  that  the  present  orien- 
tation of  cestodes  has  been  regarded  as  self-evident,  incapable  of 
proof;  and  proceeds  to  show  that,  aside  from  the  habitus  of  the 
worm,  there  is  no  evidence  in  favor  of  this  view.  In  his  own 
words:  "Meine  These  ist,  dass  dem  Geschlechtstiere  der  Ces- 
toden  ein  Kopf  iiberhaupt  fehlt,  und  sein  Hinterende  zu  einem 
Haftorgane — dem  Scolex — umgebildet  ist."  He  regards  the 
hook-bearing  tail-like  appendage  of  the  cysticercoids  as  the  homo- 
logue  of  the  ancestral  anterior  extremity  of  the  worm;  this  is 
discarded,  leaving  the  posterior  organ  of  attachment  and  the 
intermediate  growing  region  of  the  body  to  constitute  the  adult 
cestode.  "Wir  haben  in  den  Proliferationsfahigen  Scolices  also 


430          University  of  California  Publications  in  Zoology.     [VOL.  6 

Tiere,  die  ohne  ein  wahres  Vorderende,  d.  h.  einen  Kopf  zu  besit- 
zen,  mit  dem  aussersten  Hinterende  sich  an  der  Darmwand  fix- 
ieren  und  mit  ihren  relativ  vordersten  Korperende  frei  in  den 
Darm  hineinhangen. "  He  then  proceeds  to  show  that,  first,  the 
presence  of  a  differentiated  intermediate  portion  between  the 
anterior  and  posterior  segments  of  the  body,  secondly,  the  detach- 
ment of  the  posterior  segment  and  its  transformation  into  the 
sexually  mature  animal,  and  lastly,  the  location  of  the  growing- 
zone  in  the  penultimate  region  of  the  body,  are  conditions  whose 
analogues  can  be  readily  found  in  other  worms  and  also  in 
echinoderms,  bryozoans,  etc.  On  the  last  and  probably  most  im- 
portant point,  the  location  of  the  growth-zone,  he  sums  up  the 
evidence  very  briefly  as  follows : 

"Ob  wir  also  die  normalen  Wachstumserscheinungen,  ob  wir  Kegenera- 
tion  oder  die  der  autotomischen  Teilung  vorausgehenden  Processe  der  Seg- 
mentvermehrung  betrachten:  uberall  finden  wir  dass  sich  die  Wachstumzone 
beiden  genannten  Tieren  an  aussersten  Hinterende  des  Korpers  befindet. 
Bei  der  von  mir  vorgeschlagenen  Orientierungen  der  Cestoden  schaffen  wir 
also  in  bezug  auf  die  Wachstumsverhaltnisse  keinen  Ausnahmefall  sondern 
erhalten  im  Gegenteil  erst  so  die  Moglichkeit,  das  Wachstum  der  Cestoden 
durch  Proliferation  am  Collum  mit  demjenigen  anderer  Vermes  konform 
auf  zuf  assen. ' ' 

These  considerations,  arising  from  facts  of  comparative 
embryology  and  morphology  of  the  invertebrates,  taken  together 
with  those  arising  from  a  study  of  the  morphology  of  the  primi- 
tive genus  Gyrocotyle,  afford  a  warrant  for  serious  question  of 
the  validity  of  the  generally  accepted  orientation  of  cestodes. 
Furthermore,  they  constitute  a  more  or  less  successful  effort  to 
take  this  question  out  of  the  realm  of  "self-evident"  hypotheses 
incapable  of  either  proof  or  disproof  where,  as  Cohn  pointed 
out,  it  has  too  long  existed.  Further  embryological  research, 
especially  on  such  forms  as  Ampliiliiia  and  Gyrocotyle,  is  greatly 
to  be  desired ;  from  this  field  the  final  word  on  the  question  must 
be  obtained.  All  the  facts  now  at  hand,  however,  seem  to  show 
that  this  decision  will  be  in  direct  opposition  to  the  generally 
accepted  belief,  and  will  place  the  organ  of  attachment  in  ces- 
todes at  the  posterior  extremity  of  the  strobila. 


1911]  Watson:  The  Genus  Gyrocotyle.  431 

F.  SUMMARY. 

1.  The  genus  Gyrocotyle  is  composed  of  the  following  species : 
G.  rugosa,  G.  urna,  G.  nigrosetosa,  G.  fimbriata.    These  are  dis- 
tinguished on  the  basis  of  the  following  specific  characteristics : 

(1)  Character  of  folds  of  terminal  rosette. 

(2)  The  ratio  between  the  distance  from  the  opening  of  the 
uterus  to  the  tip  of  the  acetabulum,  and  the  distance  from 
the  opening  of  the  uterus  to  the  level  of  the  opening  of  the 
penis. 

(3)  Character  of  lateral  frills. 

(4)  Presence  and  distribution  of  spines. 

(5)  Size  of  tail-rosette. 

(6)  Presence  of  hooked  embryo  in  uterine  eggs. 

(7)  Presence  of  an  eversible  cirrus,  adapted  to  self -impreg- 
nation. 

(8)  Spinules  lining  ejaculatory  duct. 

(9)  Operculated  uterine  eggs. 

2.  The  normal  habitat  of  the  sexually  mature  individual  is 
in  the  spiral  valve  of  the  intestine  of  some  species  of  the  family 
Chimaeridae.     Reported   occurrences    of    G.    rugosa    in    bivalve 
molluscs  are  probably  accidental.     Nothing  is  known  of  inter- 
mediate host  or  life-cycle  of  the  parasite. 

3.  The  functional  orientation  of  Gyrocotyle  fimbriata  directs 
the  acetabulum  anteriorly,  the  rosette  posteriorly.     This  is  in 
agreement  with  Wagener's  observations  on  the  living  G.  urna, 
but  in  exact  opposition  to  Lonnberg's  observations  on  the  same 
form.    The  worm  is  capable  of  definitely  directed  locomotion  and 
is  very  active  under  favorable  conditions.     The  exploring  func- 
tion of  the  acetabulum  is  strongly  in  evidence.     The  posterior 
rosette  functions  strictly  as  an  organ  of  attachment.    The  aceta- 
bulum never  functions  as  an  organ  of  attachment. 

4.  This  functional  orientation  is  borne  out  by  evidence  from 
the  structure  of  the  central  nervous  system  and  by  the  presence 
on  the  margin  of  invagination  of  the  acetabulum  of  a  pair  each 
of  sensory  pits  and  sensory  papillae,  abundantly  innervated  by 
heavy  branches  from  the  central  nervous  system. 


432          University  of  California  Publications  in  Zoology.     tv°L-  G 

5.  The  acetabular  portion  of  the  nervous  system  is  developed 
in  connection  with  the  acetabular  sense  organs    and    with    the 
power  of  locomotion  in  a  definite  direction.    It  corresponds  to  the 
" brain"  of  Turbellaria  and  to  the  anterior  ganglionic  commis- 
sure in  Trematoda. 

6.  The  rosette  portion  of  the  nervous  system  is  developed  in 
connection  with  the  development  of  a  powerful  posterior  organ 
of  attachment,  and  is  comparable  to  the  posterior  ring-commis- 
sure in  the  posterior  sucker  of  a  heterocotylean  trematode. 

7.  The  rosette  of  Gyrocotyle  is  in  structure  and  function  a 
true  scolex,  and  corresponds  to  that  organ  in  merozoic  cestodes. 
This  correspondence  is  strikingly  shown  in  a  comparison  of  the 
nervous  system  of  the  rosette  of  Gyrocotyle  and  that  of  the  scolex 
of  the  merozoic  cestodes. 

8.  On  the  basis  of  this  evidence  from  comparative  morphology 
and  of  other  evidence  previously  adduced  from  the  embryology 
of  merozoic  cestodes,  it  is  proposed  to  regard  the  cestode  scolex 
as  a  posteriorly  situated  organ  of  attachment,  the  "neck"  or 
growing  region  as  the  antepenult  region  corresponding  to  the 
antepenult  segment  in  annelids,  and  the  proglottis  as  the  inter- 
mediate region  of  the  body.     The  anterior  extremity  has  com- 
pletely disappeared,  according  to  this  view. 

9.  The  limiting-membrane  in  Gyrocotyle  consists  of  a  sur- 
face layer,  composed  of  delicate  fibres  in  a  homogeneous  matrix, 
and  immediately  beneath  this  a  layer  of  transverse  and  a  layer  of 
longitudinal  muscle  fibres,  non-nucleated.     These  are  connected 
by  fine  processes  with  a  layer  of  large  cells  lying  in  the  paren- 
chyma of  the  body,  the  subcuticular  cells.    Some  at  least  of  these 
cells  are  to  be  regarded  as  myoblasts  of  the  cuticular  musculature. 
There  is  no  ground  for  regarding  them  as  sunken  epidermal  cells. 
There  is  no  trace  in  any  of  the  tissues  of  the  body  of  an  epithelial 
layer  of  cells.    The  lining  of  the  genital  ducts  is  a  meshwork  of 
fibres  in  a  homogeneous  matrix,  with  nuclei  scattered  through  it. 
This  passes  by  gradual  transition  into  the  non-nucleated  condition 
described  for  the  limiting  membrane  of  the  body. 

10.  The  muscle  fibres  of  Gyrocotyle  are  all  nucleated  except 
those  of  the  cuticular  musculature.     The  latter  are  attached  by 


1911]  Watson:  The  Genus  Gyrocotyle.  433 

delicate  processes  to  deeper-lying  myoblasts  (in  the  subcuticular 
layer). 

11.  The  processes  of  cell-division  in  the  maturation  of  the 
ovum  are  mitotic.  A  large  "nucleolus"  is  formed  within  the 
nucleus  and  extruded  into  the  cytoplasm.  This  process  can 
easily  be  mistaken  for  an  amitotic  figure. 

Zoological  Laboratory,  University  of  California. 
Transmitted  April  25, 1910. 


Of    TH£ 

UNIVERSITY 

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434          University  of  California  Publications  in  Zoology.     [VOL-  6 


LITERATURE    CITED. 

Barrels,  J. 

1889.  Une  nouvelle  conception  de  I'organisme  Cestode.  Rev.  Biol. 
Nord  France,  2,  18-23,  199. 

Benham,  W.  B. 

1891.  The  Platyhelmia,  Mesozoa  and  Nemertini.  In  Lankester's 
Treatise  on  Zoology,  part  IV,  1-204,  with  figs. 

Blochmann,  F. 

1896.  Die  Epithelfrage  bei  Cestoden  und  Trematoden.  Vortrag  ge- 
halten  auf  der  VI.  Jahresversammlung  der  deutschen 
zoologischen  Gesellschaft  zu  Bonn.  16  pp.,  2  pis.  Hamburg. 

Blumberg,  C. 

1877.  Ein  Beitrag  zur  Anatomic  der  Taenia  plicata,  T.  perfoliata,  und 
T.  mamillata.  Arch.  f.  wiss.  u.  prakt.  Thierhlkde,  3,  33-44. 
pi.  1,  figs.  1,  2. 

Braun,  M. 

1889.  Gyrocotyle,  Amphiptyches  und  Verwandte.  Zusammenfassender 
Bericht.  Centrbl.  Bakter.,  6,  436-441. 

1894-1900.  Cestodes.  In  Bronn's  Klassen  und  Ordnungen  des  Thier- 
reichs,  4,  I  b,  pp.  927-1731,  pis.  35-59. 

Child,  C.  M. 

1907.  Studies  on  the  relation  between  amitosis  and  mitosis.  IV  and 
V.  Biol.  Bull.,  13,  165-184,  19  figs. 

Conn,  L. 

1898.  Untersuchungen  iiber  das  centrale  Nervensystem  des  Cestoden. 
Zool.  Jahrb.  Anat.,  12,  89-160,  pis.  6-9,  text  figs.  A-J. 

1907.     Die  Orientierung  der  Cestoden.     Zool.  Anz.,  32,  51-56. 

Dean,  B. 

1906.     Chimaeroid   Fishes   and   their   development.      194   pp.,   11    pis., 

144  text  figs.     Carnegie  Institution  of  Washington. 
Diesing,  C.  M. 

1850.     Systema  Helminthum.     I;  xiii,  679  pp.     Vindobonae. 

1855.  Sechzehn  Gattungen  von  Binnenwurmern  und  ihre  Arten. 
Denkschr.,  d.  k.  Akad.  d.  Wiss.  Wien,  Math.-naturw.  Cl.,  9, 
171-185,  pis.  1-6. 


Watson:  The  Genus  Gyrocotyle.  435 

1858.  Eevision   der  Myzhelminthen.     Abtheilung   Trematoden.   Sitzb. 

k.  Akad.  d.  Wiss.  Wien,  Math.-naturw.  Cl.,  32,  207-390,  2  pis. 

1859.  Eevision  der  Myzhelminthen.  Abtheilung  Bdellideen.     Ibid.  33, 

473-513. 

1859.  Nachtrage  und  Verbesserungen  zur  Eevision  der  Myzhelmin- 
then. Ibid,  35,  421-454. 

Goto,  S. 

1891.  Diplozoon  nipponicum  n.sp.  Journ.  Coll.  Sci.  Imp.  Univ.  Japan, 
4,  151-192,  pis.  21-23. 

Grube,  E. 

1855.  Bemerkungen  iiber  einige  Helminthen  und  Meerwiirmer.  Arch. 
f.  Naturg.,  21,  I,  137-158,  pis.  6,  7. 

Haswell,  W.  A. 

1902.  On  a  Gyrocotyle  from  Chimaera  ogilbyi,  and  on  Gyrocotyle  in 
general.  Proc.  Linn.  Soc.,  N.  S.  Wales,  1902,  I,  48-54,  pi.  7. 

Hungerbiihler,  M. 

1910.  Studien  an  Gyrocotyle  und  Cestoden.  Ergebnisse  einer  von  L. 
Schultze  ausgefiihrten  zoologischen  Forschungsreise  in 
Siidafrika.  Inaug.  Diss.,  Basel.  26  pp.,  2  pis.  Also  in  Jenais. 
Denkschr.,  16,  3  Lief. 

Kofoid,  C.  A.,  and  Watson,  Edna  E. 

1910.  On  the  Orientation  of  Gyrocotyle  and  of  the  Cestode  strobila. 
Advance  print  from  Proc.  Seventh  Intern.  Zool.  Congr.,  1907, 
5  pp.,  3  figs. 

Lang,  A. 

1881.  Untersuchungen  zur  vergleichenden  Anatomie  und  Histologie 
des  Nervensystems  der  Plathelminthen.  IV.  Nervensystem 
der  Tricladen.  Mt.  Stat.  Neapel,  3,  1-53,  pis.  5,  6. 

1891.  Text-book  of  Comparative  Anatomy,  trans,  by  H.  M.  and  M. 
Bernard,  1,  pp.  133-176;  figs.  102-120. 

Lay,  G.  T.,  and  Bennet,  E.  T. 

1839.  "Fishes"  in  Zoology  of  Captain  Beechey's  voyage.  Bohn, 
London,  1839. 

Lint  on,  E. 

1891.  Notes  on  Entozoa  of  marine  fishes  of  New  England  with  de- 
scriptions of  several  new  species.  Part  II.  Eep.  U.  S.  Fish 
Comm.,  1887,  719-899,  pis.  1-15. 

Lonnberg,  E. 

1890a.  Helminthologische  Beobachtungen  von  der  Westkiiste  Nor- 
wegens.  Cestoden.  Bih.  Svenska  Ak.,  16,  IV,  5,  1-47. 


436          University  of  California  Publications  in  Zoology.     tv°L-  6 

1890b.  Ueber  Amphiptyches  Wag.  oder  Gyrocotyle  urna  (Grube  et 
Wagener)  Diesing  Verb.  Biol.  Ver.  Stockholm,  3,  55-61. 

1891.  Anatomische  Studien  tiber  Skandinavische  Cestoden.     Svenska 

Ak.  Handl.,  N.  F.  24,  VI,  1-109,  pis.  1-3,  47  figs. 

1897.  Beitrage  zur  Phylogenie  der  parasitischen  Plathelminthen. 
Centrbl.  Bakter.  22,  I,  674-684,  725-731,  figs.  1-4. 

Looss,  A. 

1894.  Die  Distomen  unserer  Fische  und  Frosche.  Neue  Untersuch- 
ungen  iiber  Bau  und  Entwicklung  des  Distomen  Korpers. 
Zoologica,  6,  Heft.  16,  1-296,  9  pis. 

Monticelli,  F.  S. 

1888.  Saggio  di  una  morfologia  dei  trematodi.  Tese  per  ottonere  la 
privata  docenza  in  Zoologia  nella  K.  Universita  di  Napoli. 
viii,  130  pp.,  ind.  1  p. 

1889a.  Sul  sistema  nervosa  dell'  Amphiptyches  urna  Grube  et  Wagener. 
Zool.  Anz.,  12,  142-144. 

1889b.  Gyrocotyle  Diesing,  Amphiptyches  Grube  et  Wagener.  Atti 
Ace.  Lincei  Kendic.  cl.  sci.  fis.  mat.  e  nat.  (4),  5,  228-230. 

1889c.  Notes  on  some  entozoa  in  the  collection  of  the  British  Museum. 
P.  Zool.  Soc.  London,  1889,  321-325,  pi.  33. 

1890.  Alcuni  considerazioni  biologiche  sul  genere  Gyrocotyle.  Atti 
Soc.  Ital.  di  Sci.  Nat.,  32,  327-329. 

1892.  Appunti  sui  Cestodaria.     Atti  E.  Accad.   Sci.  fis.  mat.  Napoli 

(2),  5,  67-78,  4  figs. 

Niemiec,  J. 

1886.  Untersuchungen  iiber  das  Nervensystem  der  Cestoden.  Arb. 
Zool.  Inst.  Wien,  7,  1-60,  pis.  1,  2. 

Olsson,  P. 

1896.  Sur  Chimaera  monstrosa  et  ses  parasites.  Mem.  Soc.  Zool. 
France,  9,  499-512,  figs.  1-9. 

Pintner,  Th. 

1880.  Untersuchungen  iiber  den  Bau  des  Bandwurmkorpers  mit  be- 
sonderer  Beriicksichtigung  der  Tetrabothrien  und  Tetra- 
rhynchen.  Arb.  Zool.  Inst.  Wien,  3,  163-242,  5  pis. 

Pratt,  H.  S. 

1909.  The  cuticula  and  subcuticula  of  trematodes  and  cestodes.  Amer. 
Nat.,  43,  705-729. 


Watson:  The  Genus  Gyrocotyle.  437 

Salensky,  W. 

1874.  Ueber  den  Bau  und  die  Entwickelungsgeschichte  der  Amphi- 
lina  G.  Wagener  (Monostomum  foliaceum  Kud.).  Z.  wiss. 
Zool.,  24,  291-342,  pis.  28-32. 

Schiefferdecker,  P. 

1874.  Beitrage  zu  Kenntniss  des  feineren  Baues  der  Taenien.  Jena. 
Zeitschr.  f.  Naturw.  8,  459-487,  pi.  16. 

Spencer,  W.  B. 

1889.  Anatomy  of  Amphiptyches  urna  Grube  et  Wagener.  Tr.  R.  Soc. 
Victoria,  1,  138-151,  pis.  11-13. 

Tower,  W.  L. 

1900.  Nervous  system  of  the  cestode  Moniezia  expansa.  Zool.  Jahrb. 
Anat.,  13,  359-384,  pis.  21-26. 

van  Beneden,  P.  J.,  et  Hesse,  C.  E. 

1864.     Recherches    sur    les  bdellodes    ou    hirudinees    et    les    trematodes 
marins.     Mem.  Ac.  Belgique,  38,  Mem.  I,  1-142,  pis.  1-13. 

Wagener,  G. 

1852.  Ueber  einen  neuen  in  der  Chimaera  monstrosa  gefundenen 
Eingeweidewurm.  Arch.  f.  Anat.  und  Physiol.,  1852,  543- 
554,  pis.  14,  15. 

1858.  Enthelminthica  No.  V.  Ueber  Amphilina  foliacea  (Monostomum 
foliaceum  Rud.)  Gyrocotyle  Diesing  und  Amphiptyches  Gr.  W. 
Arch.  f.  Natiirg.,  24,  I,  244-249,  1  pi. 

Will,  H. 

1893.  Anatomic-  von  Caryophyllaeus  mutabilis  Rud.,  ein  Beitrag  zur 
Kenntniss  der  Cestoden.  Z.  wiss.  Zool.,  56,  1-39,  pis.  1,  2, 
2  figs,  in  text. 


DESCRIPTION  OF  PLATES. 

All  figures  are  drawn  with  a  Zeiss  camera  lucida,  unless  otherwise 
stated. 


PLATE  33. 

Figs.  1-4.  Changes  in  form  of  living  Gyrocotyle,  as  seen  by  Lonnberg 
(1891,  Taf.  Ill,  figs.  34,  35,  36,  37).  Fig.  1,  the  Ligula-like  form;  fig.  2, 
rosette  extended  into  long  tube;  figs.  3  and  4,  form  ordinarily  assumed 
by  animal. 

Figs.  5  and  6,  Diesing's  figures  of  Gyrocotyle  rugosa.  (Diesing  1855, 
Taf.  1,  figs.  17,  20.) 

Figs.  7,  8,  9.  Sketches  of  the  acetabulum  of  a  living  specimen.  Figs. 
7,  9,  extended;  fig.  8,  contracted. 

acet. — acetabulum.  p.   op. — penis   opening. 


[438] 


UNIV.   CALIF.    PUBL.  ZOOL.   VOL.  6 


[WATSON]   PLATE  33 


7. 


P.  op 


PLATE  34. 

Fig.  10.  Gyrocotyle  fimbriata,  ventral.  Flattened,  stained  in  borax- 
carmine,  cleared  in  cedar-oil.  Showing  arrangement  of  spines  at  pos- 
terior extremity.  Spines  at  anterior  extremity  not  shown.  X  4. 

Fig.  11.  G.  urna,  dorsal.  Stained  flattened  specimen.  Showing  size 
and  character  of  folds  of  posterior  rosette,  and  collar  of  spines  about  the 
neck  of  the  rosette.  X  4. 

Fig.  12.  G.  fimbriata,  dorsal.     Stained  flattened  specimen.     X  4. 

Fig.  13.  G.  urna  (var.),  ventral.  Showing  distribution  of  spines  over 
whole  surface.  X  7. 

Figs.  14,  15.  G.  fimbriata.  Showing  canal-opening,  with  proboscis 
inverted,  fig.  14,  and  everted,  fig.  15.  Sketch  without  camera. 

Fig.  16.  Sagittal  section  of  longitudinal  nerve-stem,  showing  sheath- 
cells,  branch-nerves,  and  ganglion-cells  of  the  first  order.  Iron  haem- 
atoxylin-erythrosin.  X  100. 

acet. — acetabulum. 

can.  op. — canal  opening. 

gang.  1st. — ganglion  cell  of  the  first  order. 

gen.  notch — genital  notch. 

n.  b. — nerve  branch. 

n.  fib. — nerve  fibre. 

p.  op. — penis  opening. 

par. — parenchyma. 

post.  ros. — posterior  rosette. 

prob . — proboscis. 

rec.  sem. — receptaculum  seminis. 

sh.  c. — sheath  cell. 

ut. — uterus. 


[440] 


UNIV.  CALIF.    PUBL  ZOOL.   VOL.  6 


[WATSON]   PLATE  34 


acet. 


gen.  notch 
v.  op. 

ui. 


rec.sem. 


post.  ros. 


10. 


post.  ros. 


can.  op- 


15. 


post.  ros. 


11. 


16. 


PLATE  35. 

Fig.  17.  Gyrocotyle  fimbriata.     Diagram  of  the  nervous  system  of  the 
posterior  extremity.    From  Kofoid  and  Watson  (1910,  fig.  3). 

Fig.  18.  Diagram  of  the  arrangement  of  muscle-layers  in  the  saggital 
section. 

Fig.    19.  Diagram    showing   track    made    by   living     specimen     across 
dish.     Distance  traversed,  about  14cm.;  four  contractions. 

Fig.  20.  Sketch   of  network   of   excretory   canals   in   the   lateral   fold 
as  seen  in  a  living  specimen.     Zeiss-Greenough  binocular. 

Fig.  21.  Diagram,  reproductive  system,  typical  heterocotylean  trema- 
tode.     (After  Benham,  1891,  p.  51.) 

cut. — cuticle. 

cut.  trans. — cuticular  transverse  muscle. 

cut.  long. — cuticular  longitudinal  muscles. 

dist.  r.  comm. — distal  ring  commissure. 

ex.  can. — excretory  canal. 

in.  long. — inner  longitudinal  muscle. 

in.  trans. — inner  transverse  muscle. 

lat.  A— lateral  fold. 

lat.  long.  conn. — lateral  longitudinal  connective. 

marg.  ex.  sin. — marginal  excretory  sinus. 

med.  long.  conn. — median  longitudinal  connective. 

out.  long. — outer  longitudinal  muscle. 

out.  trans. — outer  transverse  muscle. 

post.  ~br.  comm. — posterior  bridge  commissure. 

subcutic.  1. — subcuticular  layer. 

vit. — vitellaria. 

v.  op. — vaginal  opening. 


[442] 


UNIV.   CALIF,    PUBL.  ZOOL   VOL.  6 


[WATSON]   PLATE  35 


post.  br.  comm. 


-^^7i  med.  long.  conn. 
lat.  long.  conn. 


- — dist.r.  comm. 


17. 


cut.  trans. 

out.  trans 
out.  long.  — 


in. 


ut. 

— cut.  long, 
subcutic.  I. 
/ 
?$&$z-in.  trans: 


PP-**  / 


ex.  can. 


/ 


19. 


w^m 


Jj 

I  It  f 

,\:    ««•    ;/-i 

SOF/ 


i/i.  /on^. 
ex.  can. 


21. 


PLATE  36. 

Figs.  22,  23.  Gyrocotyle  fimbriata,  anterior  extremity,  ventral  and 
dorsal.  Showing  sensory  pits  and  arrangement  of  spines.  From  pre- 
served specimen.  X  13. 

Fig.  24.  G.  urna  (var.).  Sketch  from  life.  Lateral  view,  expanded. 
Showing  spines,  lateral  fold  and  posterior  rosette. 

Fig.  25.  G.  fimbriata.  Dorsal  half  of  sagittal  section  of  tip  of  aceta- 
bulum,  showing  sensory  pit.  Borax-carmine,  Lyon  's  blue.  X  430. 

Fig.  26.  G.  fimbriata.  Sketch,  life,  acetabular  extremity.  Showing 
anterior  excretory  ring  and  deeper-lying  ciliated  canals. 

Fig.  27.  G.  fimbriata.  Sagittal  section  just  laterad  of  the  acetabulum. 
Showing  anterior  longitudinal  nerve  stem,  with  branches  and  anterior 
ganglionic  knot.  No  histological  detail;  position  of  giant-cells  within 
ganglion  knot  marked  by  small  circles. 

acet.  op. — acetabular  opening. 

ant.  ex.  r. — anterior  excretory  ring. 

ant.  gang.  Jen. — anterior  ganglion  knot. 

ant.  lat.  n.  st. — anterior  lateral  nerve  stem. 

cil. — cilia. 

cut. — cuticula. 

ex.  can. — excretory  canal. 

gen.  notch — genital  notch. 

lat.  /.—lateral  fold. 

par.  nuc. — parenchyma  nucleus. 

p.  op. — penis  opening. 

post.  ros. — posterior  rosette. 

sens,  pit — sensory  pit. 

sp. — spine. 

test. — testis. 

ut.  po. — uterine  pore. 

test.  n. — testicular  nerve. 


[444] 


UNIV.  CALIF.    PUBL.  ZOOL.   VOL.  6 


[WATSON]   PLATE  36 


ns.  pit 
acet.  op. 


27. 


OF    THE 

{    UNIVERSITY  J 


PLATE  37. 

Figs.  28,  29.  Gyrocotyle  fimbriata.  Spines,  from  acetabular  group. 
Teased  out.  X  1000. 

Fig.  30.  G.  fimbriata.  Spine,  from  neck  of  rosette.  From  specimen 
stained  in  borax-carmine  and  cleared  in  cedar-oil.  Showing  direction  of 
spine  and  attachment  of  muscles.  X  430. 

Fig.  31.  G.  fimbriata.  Spine  from  neck  of  rosette.  From  same  speci- 
men as  fig.  30.  Drawn  in  situ.  X  430. 

Fig.  32.  Spines  from  margin  of  anterior  end,  in  front  of  genital  notch. 
Teased  out.  X  1000. 

Fig.  33.  G.  fimbriata,  transverse  section.  Cuticula  absent.  Showing 
muscles  of  spine.  X  430.  Iron  haematoxylin. 

Fig.  34.  Same  as  fig.  33.  Showing  structure  of  socket  of  spine. 
X  1000. 

Fig.  35.  Spine  from  neck  of  rosette.     X   1000. 

muse.  fib. — muscle  fibre. 
par.  felt — parenchyma  felt. 
par.  nuc. — parenchyma  nucleus. 
protr.  m. — protractor  muscle. 
retr.  m. — retractor  muscle. 
sp. — spine. 
sp.  base — spine  base. 
sp.  sock. — spine  socket. 
sp.  tip — tip  of  spine. 


[446] 


UNIV    CALIF.    PUBL.   ZOOL.  VOL.  6 


[WATSON]    PLATE  37 


sp.  tip 


28 


sp.  tip 


29 


32. 


rotr.  m. 


•par.  nuc. 


30. 


35. 


sp.  base 


PLATE  38. 

Fig.  36.  Gyrocotyle  rugosa,  from  Spencer  (1889,  pi.  1,  fig.  1).  To  show 
size  and  character  of  lateral  folds  and  posterior  rosette  and  position  of 
genital  pores.  X  1.5,  based  on  Spencer's  reported  magnification  of  3 
which  is  possibly  an  error. 

Fig.  37-41.  Eggs  of  G.  fimbriata.  Figs.  37-40,  from  decayed  or  macer- 
ated specimens;  fig.  41,  from  living  worm.  X  500. 

acet. — acetabulum. 

ant.  br.  comm. — anterior  bridge  commissure. 

long.  n.  st. — longitudinal  nerve  stem. 

operc. — operculum. 

p.  op. — penis  opening. 

post.  br.  comm. — posterior  bridge  commissure. 

post.  ros. — posterior  rosette. 

prob. — proboscis. 

rec.  ov. — receptaculum  ovorum. 

rec.  sem. — receptaculum  seminis. 

ut.  po. — uterine  pore. 

vag. — vagina. 

vag.  op. — vaginal  opening. 

vas  def. — vas  deferens. 


[448] 


UNIV.   CALIF.    PUBL.   ZOOL.  VOL.   6 


[WATSON]    PLATE  38 


~acet. 


ant.  br.  comm. 


post.  br.  comm 

prob. 
post.  ros. 


40. 


PLATE  39. 

Fig.  42.  Gyrocotyle  fimbriata,  dorsal.     Specimen  flattened,  stained  in 
borax-carmine;  cleared  in  cedar-oil.     X  13. 

acet. — acetabulum. 

acet.  op. — acetabular  opening. 

ant.  br.  comm. — anterior  bridge  commissure. 

ant.  lat.  n.  st. — anterior  lateral  nerve  stem. 

gen.  notch — genital  notch. 

lat.  f.— lateral  fold. 

long.  n.  st. — longitudinal  nerve  stem. 

ovar. — ovary. 

p.  op. — penis  opening. 

pen.  pap. — penis  papilla. 

post.  br.  comm. — posterior  bridge  commissure. 

post.  gang.  Ten. — posterior  ganglion  knot. 

post.  ros. — posterior  rosette. 

prox.  r.  comm. — proximal  ring  commissure. 

rec.  sem. — receptaculum  seminis. 

ros.  n. — "neck"  of  rosette. 

sh.  gl. — shell  gland. 

ut.  po. — uterine  pore. 

vag. — vagina. 

vas  def. — vas  deferens. 

vit.  d. — vitelline  duct. 


[4501 


UNIV,   CALIF.    PUBL  ZOOL.  VOL  6 


[WATSON]   PLATE  39 


acet.  op. 


gen.  notch 
vag. 

pen.  pap 


long.  n.  St. 


recjsem. 
sh.  gl. 


.post.  br.  comni. 
'post.  gang.  kn. 
—vox  r.  comm. 


ros.  n. 
t.  ros. 


42. 


Of   THE 

UNIVERSITY 

OF 


PLATE  40. 

Fig.  43.  G.  fimbriata,  sagittal  section.  To  show  structure  of  aceta- 
bulum  and  attachment  of  inner  longitudinal  muscles.  Borax-carmine, 
Lyon's  blue.  X  100. 

Fig.  44.  Diagram,  showing  musculature  of  canal  opening. 

Fig.  45.  Same  as  fig.  43,  showing  detail  of  acetabular  sphincter. 
X  430. 

acet.  lum. — acetabular  lumen. 

acet.  op. — acetabular  opening. 

acet.  sphinc. — acetabular  sphincter. 

ant.  br.  comm. — anterior  bridge  commissure. 

ant.  lat.  n.  st. — anterior  lateral  nerve  stem. 

can.  op. — canal  opening. 

in.  long. — inner  longitudinal  muscle. 

in.  mer. — inner  meridional  muscle. 

in.  trans. — inner  transverse  muscle. 

out.  circ. — outer  circular  muscle. 

out.  long. — outer  longitudinal  muscle. 

out.  mer. — outer  meridional  muscle. 

out.  trans. — outer  transverse  muscle. 

rad.  fib. — radial  fibre. 

ros.  sphinc. — rosette  sphincter. 

sphinc. — sphincter. 

test. — testis. 


[452] 


UNIV,   CALIF.    PUBL.  ZOOL,  VOL  6 


[WATSON]    PLATE  40 


test. 


acet.  op. 
acpt.sphinc. 

out.  circ. 
rad.  fib. 
acet.  lum. 

in.  mer. 


out.  mer 
in.  trans, 
out.  long, 
out.  trans. 


ant.  br.  comm. 
in.  long. 


43. 


acet.  lum. 

sphinc. 

ant.  lat.  n.  st. 


45. 


PLATE  41. 

Fig.  46.  Gyrocotyle  fimbriata.  Same  specimen  as  fig.  42.  Ventral. 
Showing  vagina  and  vaginal  opening,  vesicula  seminalis,  penis-papilla 
and  ejaculatory  duct.  X  100. 

Fig.  47.  Egg  from  fifth  coil  of  uterus.  Showing  single  ovum  sur- 
rounded by  numerous  yolk-cells.  Delafield's  haematoxylin.  X  1000. 

Fig.  48.  Same,  tenth  coil  of  uterus.  Showing  division  of  ovum  and 
disintegration  of  yolk  cells.  Note  disappearance  of  nuclei  of  yolk  cells. 
X  1000. 

Fig.  49.  Yolk  cells  in  vitellarian  follicle.  Note  reduction  of  cyto- 
plasm and  formation  of  yolk-platelets.  X  1850. 

Fig.  50.  Spermatozoa  from  receptaculum  seminis,  showing  head,  tail 
and  acrosome.  X  1850. 

Fig.  51.  Ovum  in  afferent  oviduct;  note  shadow  of  yolk  nucleolus. 
X  1500. 

Figs.  52,  53,  54.  Follicle  of  ovary.  Showing  syncytial  ova  and  various 
stages  in  the  formation  and  extrusion  of  the  yolk-nucleolus.  X  1500. 

cyt.  r. — cytoplasmic  rim. 

ejac.  duct — ejaculatory  duct. 

in.  long. — inner  longitudinal  muscle. 

ov. — ovum. 

pen.  pap. — penis  papilla. 

sptz. — spermatozoa. 

ut. — uterus. 

vag. — vagina. 

vag.  op. — vaginal  opening. 

vas  def. — vas  deferens. 

yk.  c. — yolk  cell. 

yk.  gr. — yolk  platelets. 

yk.  nucleo. — yolk  nucleolus. 


[454] 


UNIV.   CALIF.    PUBL.   ZOOL.  VOL.   6 


[WATSON]    PLATE  41 


ov. 


ov. 

-yk.  c. 


ov. 


yk.  nucleo. 


52. 


k.  nucleo. 


53. 


PLATE  42. 

Fig.  55.  Gyrocotyle  fimbriata.  Transverse  section,  showing  cuticula 
and  cuticular  musculature.  Iron  haematoxylin.  X  1500. 

Fig.  56.  Showing  structure  of  muscle  fibres  of  the  inner  circular  and 
inner  longitudinal  layers.  X  1850. 

Fig.  57.  Showing  sagittal  (upper)  and  outer  transverse  (lower) 
muscle  cells.  X  1850. 

Fig.  58.  Frontal  section  of  cuticula  and  cuticular  musculature.  Cut 
through  a  fold  of  body-covering,  in  the  plane  of  the  fibres  of  the  cuticu- 
lar musculature.  X  1850. 

Fig.  59.  Showing  wall  of  receptaculum  seminis,  and  undifferentiated 
nucleated  muscle  fibres  lying  in  the  parenchyma  of  which  it  is  composed. 
X  1850. 

cut. — cuticula. 

cut.  long. — cuticular  longitudinal  muscle. 

cut.  trans. — cuticular  transverse  muscle. 

ext.  cut.  1. — external  cuticular  layer. 

in.  long.  fib. — inner  longitudinal  fibre. 

in.  trans. — inner  transverse  muscle. 

in.  trans,  fib. — inner  transverse  fibre. 

nuc. — nucleus. 

out.  long. —  outer  longitudinal  muscle. 

out.  trans. — outer  transverse  muscle. 

out.  trans,  fib. — outer  transverse  fibre. 

par.  felt — parenchyma  felt. 

par.  nu. — parenchyma  nucleus. 

sag.  fib. — sagittal  fibre. 

sub.  cut. — subcuticula. 

undif.  muse.  fib. — undifferentiated  muscle  fibre. 

vit. — vitellaria. 


[456] 


UNIV.   CALIF,    PUBL.  ZOOL,  VOL.  6 


[WATSON]    PLATE  42 


text.  cut.  l 

:_  cut. 

cut.  trans, 
cut.  long. 

sub.  cut. 
ut.  trans, 
out.  long. 


par.  nu. 


1  in.  long.  fib. 
nuc. 


56 


55 


57 


out.  trans,  fib. 


:ut 


cut.  trans. 


cut.  long, 
sub.  cut. 


58 


par.  felt 
par.  nu. 


par.  nu 


undif.  muse, 


Of  THE 

(  UNIVERSITY   j 

IUF< 


PLATE  43. 

Fig.  60.  Gyrocotyle  fimbriata.  Transverse  section  through  ciliated 
excretory  canal.  Showing  circular  muscle  coat.  Iron  haematoxylin.  X 
1000. 

Fig.  61.  Longitudinal  section  through  ciliated  excretory  canal  (taken 
at  one  side  of  attachment  of  cilia).  Showing  circular  muscle  coat.  Iron 
haematoxylin.  X  1000. 

Figs.  62,  63.  Flame  cells.     X  1500. 

Fig.  64.  Cells  of  prostate  gland.     X  1500. 

Fig.  65.  Sagittal  section  through  penis  papilla  and  ejaculatory  duct. 
X  100. 

can. — canal. 

cil. — cilia. 

circ.  muse.  1. — circular  muscle  layer. 

ejac.  duct — ejaculatory  duct. 

fl. — flame. 

long.  muse.  1. — longitudinal  muscle  layer. 

in.  long. — inner  longitudinal  muscle. 

pa  r. — pa  renchyma . 

par.  nu. — parenchyma  nucleus. 

pen.  pap. — penis  papilla. 

prost.  d. — prostate  duct. 

prost.  gl. — prostate*  gland. 

rad.  muse.  f. — radial  muscle  fibre. 

spnl. — spinule. 


[458] 


UNIV.   CALIF.   PUBL.  ZOOL.  VOL.  6 


[WATSON]    PLATE  43 


ejac.  duct 
circ.  muse,    . 
.  m«sc.  ^ 


65 


64 


PLATE  «, 

Kg.  CS.  gyrerefrte  fm+n*t»L    Ftan  pesterair  ga»gli««e 
S**giio«  ««Us  of  first  writer  sand  *  £»jnf£*wi  wM  «f  tlw 

Cc 


trrai 

whi  ck  &  brmiwA  to  tbe  OT^TV  n  «av«i  «C.    X 


of 

^.  Di  Ji^ 

:      :.  --    l 


.  t*t.  <L  —  efferent  riteUix 

>•;      p»n^li<  .   :•:  .    of  1  :•;   finl 


,,; 


UNIV.   CALIF.    PUBL.  ZOOL.  VOL.  8 


[WATSON]   PLATE  44 


vit.  d. 


yk.  res. 


PLATE  45. 

Figs.  70,  75.  Gyrocotyle  fimbriata.  Sagittal  section,  nearly  median. 
Diagrammatic.  X  13. 

Figs.  71,  72,  73.  Transverse  sections,  showing  (71)  emergence  of 
ductus  seminalis  from  receptaculum  seminis;  (73)  fusion  of  the  efferent 
vitelline  duct  with  the  efferent  oviduct,  which  thus  becomes  the  uterus. 
X  100. 

Fig.  74.  Sagittal  section  through  dorsal  half  of  neck  of  funnel.  Show- 
ing contrast  between  cuticula  of  funnel  cavity  and  of  the  surface  of  the 
body.  X  1000. 

acet. — acetabulum. 

cut. — cuticula. 

duct.  sem. — ductus  seminalis. 

ef.  ovd. — efferent  oviduct. 

ef.  vit.  d. — efferent  vitelline  duct. 

ejac.  duct — ejaeulatory  duct. 

ex.  can. — excretory  canal. 

in.  long. — inner  longitudinal. 

lat.  long.  conn. — lateral  longitudinal  connective. 

long.  n.  st. — longitudinal  nerve  stem. 

mus.  bd. — muscle  bundle. 

oot. — ootype. 

ovar.;  ov. — ovary. 

post.  ros. — posterior  rosette. 

pros.  gl. — prostate  gland. 

rec.  ovor. — receptaculum  ovorum. 

rec.  sem. — receptaculum  seminis. 

subcutic.  1. — subcuticular  layer. 

sh.  gl. — shell  gland. 

test. — testis. 

ut. — uterus. 

ut.  c. — uterine  coil. 

vag. — vagina. 

vit. — vitellaria. 

vit.  d. — vitelline  duct. 


[462] 


UNIV,    CALIF.    PUBL   ZOOL.  VOL.   8 


[WATSON]    PLATE  45 


post.  ros. 


rec.  sem. 


miduct.  sem. 


ef.  vit.  d. 


cut. 

subcutic.  I 
ex.  can. 

in.  long. 


.bd. 


mas 


rec.  sem. 
— oot. 
ef.  vit.  a. 

mzz^^it. 

Lei.  vit,  d. 
sh.  gl. 
mus.  bd. 
in.  long. 


74. 


75. 


' 


PLATE  46. 

Fig.  76.  Gyrocotyle  fimbriata.  Median  sagittal  section,  posterior  ex- 
tremity. Showing  funnel,  canal,  funnel-opening,  canal-opening  and  sec- 
tions of  the  ring  commissures  of  the  nervous  system  of  the  posterior 
extremity.  X  100. 

Fig.  77.  Same,  to  left  of  median.  Reconstruction  of  five  sections, 
showing  lateral  view  of  nervous  system.  Faint  dotted  lines  indicate 
course  of  nerves  as  shown  in  the  neighboring  sections;  heavy  dotted  lines 
indicate  position  of  funnel  with  reference  to  the  central  nervous  system. 
X  100. 

can.  op. — canal  opening. 

ex.  can. — excretory  canal. 

lat.  anast. — lateral  anastomosis. 

lat.  long.  conn. — lateral  longitudinal  connective. 

post.  br.  comm. — posterior  bridge  commissure. 

post.  gang.  Jen. — posterior  ganglion  knot. 

prox.  r.  comm. — proximal  ring  commissure. 

ros.  n.  st. — rosette  nerve  stem. 

ros.  r.  comm. — rosette  ring  commissure. 

ros.  sphinc. — rosette  sphincter. 

</'• — tope. 


[464] 


UNIV.   CALIF.    PUBL.   ZOOL.  VOL.   8 


[WATSON]    PLATE  46 


ros.  sphinc. 
ros.  n.  st. 

r.  comm. 


can.  op. 
t.  br.comm. 


ex.  can. 


ros.  n.  st. 
ros.  r.  comm. 

lat.  lone,  conn 

\\\ 

\A\>  lat.  anast. 

lat.  long,  conn 

>,'V  \v^       prox.  r.  comm 


post.  gang.  kn. 


PLATE  47. 

Fig.  78.  Nervous  system  of  Moniezia  expansa,  after  Tower  (1900). 
Fig.  79.  Nervous  system  of  Triclad;   after  Lang  (1881). 
Fig.  80.  G.  nigrosetosa,  Haswell  (1902,  pi.  VII,  fig.  1). 

Fig.  81.  Same,   egg,    showing   operculum.       Haswell     (1902,     pi.     VII, 
fig.  7). 

ant.  br.  comm. — anterior  bridge  commissure. 

ant.  gang.  kn. — anterior  ganglion  knot. 

ant.  r.  comm. — anterior  ring  commissure. 

dist.  r.  comm. — distal  ring  commissure. 

lat.  long.  conn. — lateral  longitudinal  connective. 

long.  n.  st. — longitudinal  nerve  stem. 

med.  long.  conn. — median  longitudinal  connective. 

post.  br.  comm. — posterior  bridge  commissure. 

post.  gang.  kn. — posterior  ganglion  knot. 

prox.  r.  comm. — proximal  ring  commissure. 


[460] 


UNIV.   CALIF.    PUBL.   ZOOL.  VOL,   8 


[WATSON]    PLATE  47 


Ions,  n,  st. 


ant.  sans.  kn. 
-  ant  r.  comm. 


post.  br.  comm. 
post.  sans.  kn. 

prox.  r.  comm. 

med.  Ions.  conn. 

at.  Ions.  conn. 


'dist.  r.  comm. 


ant.  br.  comm. 


81. 


Ions.  n.  st. 


prox.  r.  comm. 


79. 


Of    THE 

UNIVERSITY 

OF 


PLATE  48. 

Figs.    82,    83.  Photographs    of   living    specimens    of    G.   fimbriata    and 
G.  urna  (var.)     All  in  state  of  contraction.     About  natural  size. 

Figs.  84, '85.  G.  urna,  from  Wagener  (1852,  pi.  14,  figs.  1,  2). 


[408] 


UNIV.   CALIF.    PUBL.   ZOOL.  VOL. 


[WATSON]    PLATE  48 


82 


83 


85 


84 


UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS— (Continued) 

Vol.  8.    1.  Some  Observations  on  the  Nervous  System  of  Copepoda,  by  O.  O. 

Esterly.    Pp.  1-12,  plates  1-2.    January,  1906 .25 

2.  (IX)*    Ostracoda  of  the    San    Diego    Region.     1.  Halocypridae,  by 

Chancey  Juday.    Pp.  13-38,  plates  3-7.    April,  X906 .30 

3.  (X)   The  California  Shore  Anemone,  Bunodactis  xanthogrammica,  by 

Harry  Beal  Torrey.    Pp.  41-46,  plate  8,  April,  1906. 

4.  (XI)  Sexual  Dimorphism  in  Aglaophenia,  by  Harry  Beal  Torrey  and 

Ann  Martin.    Pp.  47-52,  9  text-figures.    April,  1906. 

Nos.  3  and  4  in  one  cover. .15 

6.  (XII)  New  Copepod  Fauna  from  the  San  Diego  Region,  by  Calvin  Olin 

Esterly.    Pp.  53-92,  plates  9-14.    December,  1906 .36 

6.  (XII)  Dinoflagellata  of  the  San  Diego  Region,  EL    On  Triposolenia,  a 

New  Genus  of  the  Dinophysidae,  by  Charles  Atwood  Kofoid.  Pp. 
93-116,  plates  15-17. 

7.  A  Discussion  of  the  Species  Characters  in  Triposolenia.    I.  The  Nature 

of  Species  Characters.  II.  The  Adaptive  Significance  of  Species 
Characters.  III.  The  Coincident  Distribution  of  Related  Species. 
By  Charles  Atwood  Kofoid.  Pp.  117-126. 

8.  On  the  Significance  of  the  Asymmetry  in  Triposolenia,  by  Charles 

Atwood  Kofoid.    Pp.  127-133. 

Nos.  6,  7,  and  8  in  one  cover.    December,  1906 .36 

9.  (XIV)  Ostracoda  of  the  San  Diego  Region.    II.  Littoral  Forms,  by 

Chancey  Juday.    Pp.  135-156,  plates  18-20. 

10.  (XV)  Cladocera  of  the  San  Diego  Region,  by  Chancey  Juday.    Pp. 

157-158,  1  text  figure. 

Nos.  9  and  10  in  one  cover.    January,  1907.. .      .26 

11.  (XVI)  The  Marine  Fishes  of  Southern  California,  by  Edwin  Chapin 

Starks  and  Earl  Leonard  Morris.    Pp.  159-251,  plate  21.  March,  1907.      .75 

12.  Biological  Studies  on  Corymorpha.    II.  The  Development  of  C.  palma 

from  the  Egg.  By  Harry  Beal  Torrey.  Pp.  253-298,  33  text  figures. 
June,  1907 ~ .50 

13.  (XVII)  Dinoflagellata  of  the  San  Diego  Region,    in.  Descriptions  of 

New  Species.  By  Charles  Atwood  Kofoid.  Pp.  299-340,  plates  22-23. 
April,  1907  - ._ .50 

14.  The  Structure  and  Movements  of  Condylostoma  patens,  by  John  F. 

Bovard.    Pp.  343-368,  21  text  figures.    September,  1907 36 

Index,  pp.  369-383. 

Vol.  4.  1.  The  Ascidians  Collected  by  the  United  States  Fisheries  Bureau  steamer 
Albatross  on  the  Coast  of  California  during  the  Summer  of  1904,  by 
William  Emerson  Ritter.  Pp.  1-52,  plates  1-3.  October,  1907 .50 

2.  (XVIII)  Behavior  of  the  Starfish  Asterias  forreri  de  Lcrriol,  by  H.  S. 

Jennings.    Pp.  53-185,  19  text  figures.    November,  1907 1.00 

3.  (XIX)  The  Early  LifeJEEistory  of  Dolichoglossus  pusillus  Ritter,  by  B. 

M.  Davis.    Pp.  187-226,  plates  4-8.    March,  1908 .50 

4.  Notes  on  two  Amphipods  of  the  Genus  Corophium  from  the  Pacific 

Coast,  by  J.  Chester  Bradley.    Pp.  227-252,  plates  9-13.    April,  1908.      .30 

5.  (XX)  The  Incrusting  Chilostomatous  Bryozoa  of  the  Western  Coast  of 

North  America,  by  Alice  Robertson.  Pp.  253-344,  plates  14-24,  May, 
1908 . .. 1.00 

6.  (XXI)  On  Exuviation,  Autotomy,  and  Regeneration  in  Cerattum,  by 

Charles  Atwood  Kofoid.    Pp.  345-386,  with  text  figures. 

7.  (XXII)  Notes  on  some  Obscure  Species  of  Ceratium,  by  Charles  Atwood 

Kofoid.    Pp.  387-393. 

Nos.  6  and  7  in  one  cover.    April,  1908 .50 

Index,  pp.  395-400. 
Vol.  5.    1.  The  Biota  of  the  San  Bernardino  Mountains,  by  Joseph  Grinnell.    Pp. 

1-170,  plates  1-24.    December,  1908 _..... 2.00 

2.  Birds  and  Mammals  of  the  1907  Alexander  Expedition  to  Southeastern 

Alaska.    Pp.  171-264,  pis.  25-26,  figs.  1-4.    February,  1909  .75 

3.  Three  New  Song  Sparrows  from  California,  by  Joseph  Grinnell.    Pp. 

265-269.    April  9,  1909  05 

4.  A  New  Harvest  Mouse  from  Petaluma,   California,  by  Joseph  Dixon. 

Pp.  271-273.    August  14,  1909   05 

5.  A  New  Cowbird  of  the  Genus  Molothrus,  with  a  note  on  the  Probable 

Genetic  Relationships  of  the  North  American  Forms,  by  Joseph 
Grinnell.  Pp.  275-281,  1  text  figure.  December,  1909 .05 

6.  Two  New  Rodents  from  Nevada,  by  Walter  P.  Taylor.    Pp.  283-302, 

plates  27-29. 

7.  A  Northern  Coast  Form  of  the  Calif  ornia  Gray  Fox,  by  Joseph  Dixon. 

Pp.  303-305. 

Nos.  6  and  7  in  one  cover.    February,  1910 „•. ,20 


*  Roman  numbers  indicate  sequence  of  the  Contributions  from  the  Laboratory  of  the 
Marine  Biological  Association  of  San  Diego. 


UNIVERSITY    OF    CALIFORNIA  PUBLICATIONS-(CONTINUED) 

8.  Two  Heretofore  Unnamed  Wrens  of  the  Genus  Thryomanes,  by  Joseph 

Grinnell.    Pp.  307-309. 

9.  The  Savannah  Sparrow  of  the  Great  Basin,  by  Joseph  Grinnell.    Pp. 

311-316. 

10.  A  Second  Record  of  the  Spotted  Bat  (Euderma  maculatum)  for  Cali- 

fornia, by  Joseph  Grinnell.    Pp.  317-320,  plate  30. 

Nos.  8,  9,  and  10  in  one  cover.    February,  1910 15 

11.  Mammals  of  the  1908  Alexander  Alaska  Expedition,  with  Descriptions 

of  the  Localities  Visited  and  Notes  on  the  Flora  of  the  Prince  Wil- 
liam Sound  Region,  by  Edmund  Heller.  Pp.  321-360,  plates  31-32. 

12.  Birds  of  the  1908  Alexander  Alaska  Expedition,  with  a  Note  on  the 

Avifauna!  Relationships  of  the  Prince  William  Sound  District,  by 
Joseph  Grinnell.  Pp.  361-428,  plates  33-34,  9  text-figures. 

Nos.  11  and  12  in  one  cover.    March,  1910 $1.00 

Index,  pp.  429-440. 

1.  (XXm)  On  the  Weight  of  Developing  Eggs.    Part  I,  The  Possible 

Significance  of  Such  Investigations,  by  William  E.  Bitter;  Part  II, 
Practicability  of  the  Determinations,  by  Samuel  E.  Bailey.  Pp.  1-10. 
October,  1908  10 

2.  (XXIV)  The  Leptomedusae  of  the  San  Diego  Region,  by  Harry  Beal 

Torrey.    Pp.  11-31,  with  text  figures.    February,  '1909  , ...      .20 

3.  (XXV)  The  Ophiurans  of  the  San  Diego  Region,  by  J.  F.  McClen- 

don.     Pp.  33-64,  plates  1-6.     July,  1909 30 

4.  (XXVI)  Halocynthia  johnsoni  n.  sp.:    A  comprehensive  inquiry  as  to 

the  extent  of  law  and  order  that  prevails  in  a  single  animal  species, 

by  Wm.  E.  Ritter.    Pp.  65-114,  plates  7-14.    November,  1909 50 

5.  (XXVII)  Three  Species  of  Cerianthus  from  Southern  California,  by 

H.  B.  Torrey  and  F.  L.  Kleeberger.  Pp.  115-125,  4  text-figures. 
December,  1909  10 

6.  The  Life  History  of  Trypanosoma    dimorplion,    Dutton   &    Todd,    by 

Edward  Hindle.  Pp.  127-144,  plates  15-17,  1  text-figure.  December, 
1909 50 

7.  (XXVIII)   A   Quantitative  Study  of  the  Development  of  the  Salpa 

Chain  in   Salpa   fmiformis-runcinata,  by  Myrtle  Elizabeth  Johnson. 

Pp.  145-176.    March,  1910 35 

8.  A  Revision  of  the  Genus  Ceratocorys,  Based  on  Skeletal  Morphology, 

by  Charles  Atwood  Kofoid.    Pp.  177-187.    May,  1910 10 

9.  (XXIX)  Preliminary  Report  on  the  Hydrographic  Work  Carried  on  by 

the  Marine  Biological  Station  of  San  Diego,  by  George  F.  McEwen. 

Pp.  189-204;  text-figure  and  map.    May,  1910 15 

10.  (XXX)  Biological  Studies  on  Corymorpha.    III.  Regeneration  of  Hy- 

dranth  and  Holdfast,  by  Harry  Beal  Torrey.  Pp.  205-221;  16  text- 
figures. 

11.  (XXXI)  Note  on  Geotropism  in  Corymorpha,  by  Harry  Beal  Torrey. 

Pp.  223-224;  1  text-figure. 

Nos.  10  and  11  in  one  cover.    August,  1910 20 

12.  The  Cyclostomatous  Bryozoa  of  the  West  Coast  of  North  America,  by 

Alice  Robertson.    Pp.  225-284;  plates  18-25.    December,  1910 60 

13.  Significance  of  White  Markings  in  Birds  of  the  Order  Passeriformes, 

by  Henry  Chester  Tracy.    Pp.  285-312.    December,  1910 25 

14.  (XXXIII)  Third  Report  on  the  Copepoda  of  the  San  Diego  Region,  by 

Calvin  Olin  Esterly.    Pp.  313-352;  plates  26-32.    February,  1911 40 

15.  The  Genus  Gyrnroiyle,  and  Its  Significance  for  Problems  of  Cestode 

Structure  and  Phylogeny,  by  Edna  Earl  Watson.  Pp.  353-468;  plates 
33-48.  June,  1911 1.00 

1.  Two  New  Owls  from  Arizona,  with  Description  of  the  Juvenal  Plum- 

age of  Strix  occidcntaUs  occidcntaUs  (Xantus),  by  Harry  S.  Swarth. 

Pp.  1-8.    May,  1910 10 

2.  Birds  and  Mammals  of  the  1909  Alexander  Alaska  Expedition,   by 

Harry  S.  Swarth.   Pp.  9-172;  plates  1-6;  3  text-figures.   January,  1911.    1.50 

3.  An  Apparent  Hybrid  in  the  Genus  Dendroica,  by  Walter  P.  Taylor. 

Pp.  173-177.    February,  1911  - 05 

4.  The  Linnet  of  the  Hawaiian  Islands:   a  Problem  in  Speciation,  by 

Joseph  Grinnell.    Pp.  179-195.    February,  1911  _.       .15 

5.  The  Modesto  Song  Sparrow,  by  Joseph  Grinnell.     Pp.  197-199.     Feb- 

ruary, 1911  05 

6.  Two  New  Species  of  Marmots  from  Northwestern  America,  by  H.  S. 

Swarth.    Pp.  201-204.    February,  1911  _ -. 05 

1.  The   Vertical   Distribution   of  Eucalanus   elongatus   in  the   San  Diego 

Region  during  1909,  by  Calvin  O.  Esterly.    Pp.  1-7.    May,  1911 10 


NON-CIRCULATING  BOOK 


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8RARY 


